Gather all the ingredients.

To a wok (I use a 10" carbon steel wok; use discount code “JOC10“ for 10% off) or large frying pan, add ½–¾ cup neutral oil, ¼ cup toasted sesame oil, 2 cloves garlic (sliced), 2 slices ginger, and 2–3 green parts of Tokyo negi (naga negi; long green onion) (or 4 green onions).

Heat the oil mixture on low heat. Cook and slowly extract the flavors from the aromatics without burning them, for about 15 minutes from the time the oil starts sizzling. Tip: The oil will become bitter if your aromatics burn, so take care to avoid this.

After 15 minutes, turn off the heat. Remove the aromatics from the oil with a fine-mesh skimmer and discard them.

With the stove‘s heat still off, add ⅓ cup gochugaru (Korean pepper flakes) and ½ tsp Sichuan peppercorns to the pan.

Quickly stir and infuse the oil with the chili flakes and peppercorns using the oil‘s residual heat. The oil will sizzle when the mixture is first added and then fizzles as it cools. Allow it to steep and then cool completely to room temperature, for about 30 minutes. Once cooled, transfer the La-yu to a mason jar. Optionally, you can strain the chili flakes and peppercorns, but I like to keep them in the jar to continue infusing the oil; I also consume the chili flakes along with the chili oil. Once the La-yu has cooled, you can add 1 Tbsp toasted sesame oil (optional) to the jar of chili oil as a finishing touch. Sesame oil loses its fragrance when heated, so adding a little bit of toasted sesame oil will boost the sesame flavor and aroma.

You can add a bit of La-yu to spice up any dish! We often use La-yu to season Japanese-style Chinese foods (Chuka ryori). You can drizzle it directly onto dishes like Miso Ramen, Black Sesame Dan Dan Noodles, and Mapo Tofu. Try it in a dipping sauce for Gyoza (Japanese Potstickers), Vegetable Gyoza, and Pork Shumai. La-yu is also delicious in a dressing for blanched vegetables like Chrysanthemum Greens Salad or in a marinade for dishes like Spicy Japanese Pickled Cucumbers and Cucumber and Chicken Marinated in Chili Oil.

Store the La-yu in a clean glass jar for 1–2 months in the refrigerator. Chili oil can go bad and should be discarded if it has a rancid smell or a very unpleasant flavor.