I’ve been getting a little obsessed with chili oil. A little…lost in the sauce so to speak. Here’s some notes and general thoughts on chili oil.

Chili Extraction

There are two main ways of extracting flavor from chilies with oil: hot flash or slow infusion. A hot flash basically means you heat up the oil until it’s really hot, almost smoking , i.e. 375F. You pour it over the chilies in one dramatic swoop. A slow infusion is less dramatic. You heat the oil and infuse the chilies at a lower temperature, say 200-250F.

In my experiments, the hot flash produces a noticably more intense flavor with some roasted notes. However, with that flavor, there is some bitterness. The slow infusion comes out milder, but no bitterness. That said I’ve only tried at the above temperatures. Perhaps a slow infusion at 250-300F or a hot flash at 325F could be better?

Interestingly enough, the hot flash creates an oil with the chili pieces noticably suspended in the oil, while the slow infusion results in an oil with the pieces all at the bottom. I suspect this is because the chili pieces are more intensely fried in the hot flash one, which either dissolves more soluble materials into the oil, making them lighter, or causes the pieces to unfurl and be more buoyant.

In some of the Chinese videos that I’ve watched, people do a sort of hybrid style where you add hot oil multiple times, with the idea to almost “temper” the oil, i.e. not put such a large quantity of hot oil into the chilies all at once. I could see that working too. They also temper with baijiu, i.e. strong Chinese liquor. That could also potentially be another avenue for extraction since alcohol is known to extract more flavor compounds than water? Capsaicin is soluble in alcohol, so maybe this could boost spiciness?

This does put into question whether the ratio of oil to solid material matters. I usually make the Serious Eats chili crisp recipe by Sohla El-Waylly. It uses the hot flash method, but it also includes a lot of other ingredients like ginger, cardamom, cumin, sugar, mushroom powder, etc. Perhaps the sheer quantity of solids means more thermal mass and therefore less overcooking?

I’ve also thought about doing a really low and slow extraction, say by using a sous vide machine. You do run into food safety issues, since the chilies can contain botulism.

Alternatively you could try doing multiple extractions at different temperatures or even blending different styles.

Oil Type

The easiest oil to use is a neutral oil of your choosing. It won’t add any flavor, which will let the chilies shine through. This is fairly important for experiments since you don’t want the taste of the oil to obscure results (I learned this the hard way).

But there are some other options. Classic Sichuan oil is caiziyou, or roasted rapeseed oil. It’s hard to find in the US, but you can get it at more and more Chinese supermarkets or online at Mala Market. At a Chinese supermarket, you’ll probably have to read some Chinese to make sure you’re buying the right stuff. Caiziyou is nutty, roasted, almost like a milder sesame oil. It’s great stuff to cook with and it does make a nice chili oil. Budget-wise it is more expensive, especially if you’re buying from Mala Market.

I’ve also seen people use clarified butter, like here, or beef fat like in hot pot bases. I imagine an olive oil could be good if you stick to slow infusion.

Of course there are also combinations that could be made. Maybe a chili oil with a little spike of beef fat just for flavor.

Chili Type

I usually keep quite a few different kinds of dried chilies around. Right now I have Thai birds-eyes, er ting jiao, xiao mi la, kashmiri, Japones. Of course it’s hard to determine what exactly a lot of chilies are, since there could be multiple names depending on the country. Perhaps Japones are really Heaven-Facing chilies. Or xiao mi la is birds-eye.

I used to spike the oil with some extra spicy chilies like ghost peppers or Carolina reapers. I stopped doing that because they were way more expensive than other chilies, it was extremely painful to seed them and grind, and I wasn’t convinced they actually added that much heat. One or two ghost peppers could easily be matched by a couple handfuls of birds-eye or xiao mi la. Especially since these super hot peppers are not always consistent in spice level. I did once make a chili oil with chocolate bhutlah that was delightfully spicy.

I also used to spike the oil with some chipotle peppers to add some smokiness. I might do an experiment to see how much of a difference that actually made.

Spices & Aromatics

Recipes run the gamut of no spices at all to lots and lots of spices. Generally I’m of the view that more spices are better. But this might be worth testing. I usually add star anise, black pepper (often omitted, idk why), cumin, Sichuan peppercorn, black cardamom. Potentially also cinnamon, and sand ginger.

There’s also aromatics like garlic, ginger, scallions, orange peel, etc. In Sohla’s crisp recipe, you fry a bunch of crispy shallots and garlic chips before making the oil. That way the oil gets infused with lots of shallot and garlic flavor. I do love that, but it is a lot of work.

Seasoning

Should you season the chili oil? Most recipes do call for some salt, which interestingly is not soluble in oil. I guess the salt ends up sticking to the chilies and therefore seasoning that aspect. Some recipes go as far as adding sugar, MSG, and other MSG-alternatives. This is where the ontology of the chili oil matters¹: Are you making a condiment or an ingredient? In my view, a condiment should be seasoned sufficiently that it has some sort of inherent tastiness. You’d be willing to eat a spoonful of ketchup or a spoonful of mayo, even if it’d be a little intense. An ingredient does not have to fulfill that requirement. Nobody’s just eating a spoonful of flour. So a chili oil that’s an ingredient will omit sugar and MSG and taste a little bland. That’s fine if you’re adding it to a dish like a cold poached chicken, where there will be other seasoning. A chili oil that’s a condiment will taste balanced on its own.

I do think if you add seasoning, you should go all the way and add sugar, salt and MSG. They balance each other out really nicely.

If you add seasoning, you could be veering into a chili sauce or a chili crisp. Chiu chow chili sauce is a great example. For a lot of people, especially in the US, what they consider chili oil is actually chili crisp, specifically Lao Gan Ma, the most popular brand by far. Lao Gan Ma actually has douchi or fermented black beans. Note that these are fermented black soy beans, not the black beans that we eat in the West. Personally I find douchi a little too strong of a flavor. They’re intensely salty and can overpower the rest of the ingredients.

It is important to note that the oil will stay a little bland regardless because salt does not dissolve into oil. Interestingly enough it appears that sugar does dissolve.

Chili Grinding

For the longest time I used a spice grinder to blitz up the chilies. It was fast and simple. I never loved the texture I got though. You’d end up going too fine too quickly. Plus it tended to create a lot of inhalable dust which made the process pretty painful.

I’ve recently switched over to toasting the chilies in a tiny bit of oil, then pounding them in a mortar and pestle. It’s definitely more manual labor, but you end up with these beautiful large flakes that have great texture. It’s also releases less dust into the air. You do have to make sure all of the chilies are properly toasted. They should be shiny, lightly puffed up, and brittle. Otherwise you end up with these large chunks that are too flexible to be ground down and end up mixed into the flakes.

If we’re getting really nerdy here (and hey, this is already pretty nerdy), I’d wonder about the particle distribution of grinding chilies and how that affects flavor extraction. As any coffee nerd can tell you, a spice grinder is pretty awful for grinding coffee because it produces a very uneven particle distribution. You can end up with what are called fines and boulders, fines being tiny, dust-like pieces of coffee that create bitterness in the cup, and boulders being large chunks that create sourness or emptiness in the cup. A mortar and pestle isn’t that much better. If anything you end up more bimodal. The end result is a bunch of large flakes covered with very fine chili dust. Likely due to the combination of pounding and grinding motions in the mortar and pestle. The pounding breaks the chilies into big chunks, and the grinding produces the fine powder.

Is there a way to get better particle distribution? You could in theory sift the chilies. But often times the powder appears stuck to the flakes a little bit.

Styles

So far we’ve mostly been talking about Chinese style chili oil, specifically Sichuan style. But what about other chili oils? Salsa macha is a very popular Mexican style. And you could argue that a tadka is essentially an ad-hoc chili oil made at the last second. Could you make a batch of Indian chili oil in advance, say by infusing mustard seeds, curry leaves, cumin and coriander in some ghee and substitute it for a tadka? I bet you could.

As for more European flavors, ChefSteps does an interesting Thanksgiving flavored oil. I bet a Calabrian chili oil would be incredible.

Experiments

As you can see, there’s a lot of questions and ideas here. Therefore, I’m gonna need to do some experiments! But first, we should think about methodology and potential issues with the experiments. The most important criterion for an experiment is reproducibility. Unfortunately, that is rather hard with chili oil, because the chilies are organic compounds with variable spiciness. We’re also using manual grinding so grind size is not easily controllable either. This means that while we can grind up a batch of chilies, use them in two different oils, and compare, we can’t necessarily compare these oils to oils from a separate experiment. Of course we should still try to make the experiments as reproducible as possible, so we should standardize the chili blend, ratio, and so on.

It’s also important to make the base oil as neutral as possible. I tried doing an experiment with caiziyou as the base oil, and its nuttiness occluded any differences between the two chili oils.

Of course, like coffee, you can never get a fully reproducible setup. Instead it’s probably best to make a bunch of oils, do some experiments, then learn about the general variables and how they affect the flavor. In coffee that’s grind size, temperature, time, ratio, dose, brew style. Chili oil has likely similar variables.

Anyways, on to the potential experiments. Here are a few that I have in mind:

• Infuse chilies at different temperatures
• Hot flash chilies at different temperatures
• Adjust the ratio of chilies to oil
• Add alcohol to extract more flavor
• How much do the spices actually affect the flavor?
• Sous vide chili oil
• Mortar and pestle vs spice grinder
• Add oil for a hot flash multiple times.
• Does stirring matter?

I’d love to hear if someone has other experiment ideas or other thoughts about chili oil. Feel free to reach out at nick@nicholasyang.com!