Methods

1. Preheat the oven to 400°F.
2. Place the onions, tomatoes, and garlic on a baking sheet, drizzle with oil and sprinkle evenly with 1/2 teaspoon salt. Roast until the vegetables are cooked and the onions are starting to caramelize on the side touching the pan, about 25 to 35 minutes. Remove from the oven, take off the garlic peels, discarding them, and place the roasted tomatoes, onions, and peeled garlic in a blender, and set aside.
3. While the vegetables are roasting, prepare the dried chillies. Remove the stems and the seeds from the Resham Patti and place in a medium bowl. For the Sirārakhong Hāthei, remove the stems, leaving the seeds in the chillies, and transfer to the bowl with the Resham Patti. Cover the chillies with boiling water, place a plate on top of the bowl to keep the steam in, and allow the chillies to sit for 30 minutes.
4. Remove the rehydrated chillies from the water, reserving the soaking liquid, and place them in a blender along with the roasted vegetables. Add the remaining 1 teaspoon salt, lime juice and 1/4 cup chilli soaking liquid, and blend until smooth. If you want the sauce a little thinner, keep adding some of the chilli soaking liquid a couple tablespoons at a time, blending to combine, until you reach the desired consistency. Taste for salt and adjust seasonings, as necessary. (I find that this sauce can take a lot of salt to round out the flavors of the chillies. Start with the recommended amount and then work your way up adding a pinch or two at a time until you reach the right taste for you.)
5. Use immediately, or refrigerate in an airtight container for up to 7 days.

Bonus recipe: Quick & Easy Chilaquiles for 1

Heat 1/2 to 3/4 cup of the red chile sauce in a small skillet over medium heat, adding a couple teaspoons of water to thin out the sauce, if necessary (you want it to be able to coat the chips easily). Add in a couple big handfuls of your favorite tortilla chips—I love Have A' Corn Chips—stir to coat in the sauce and cook a couple minutes to heat through. Transfer to a plate and garnish with a fried egg + the toppings of your choice (we like crumbled queso fresco or cotija, cilantro, red onions, and avocado).