¼cupneutral cooking oil, such as canola oil or grapeseed oil, or as needed
½red onion, peeled and quartered
8garlic cloves, peeled
1large tomato, or 2 small tomatoes, stemmed and quartered
Juice of 3 limes
¼bunch cilantro
1tspkosher salt
1tspblack pepper
Instructions
Stem all the chiles and then pour out and discard the seeds. You don’t have to worry about getting every last seed removed; it’s fine if some end up in the salsa.
Warm the cooking oil in a frying pan over medium-low heat. Make sure the oil is at least 1⁄16 inch deep—a little more than just a coating.
Once the oil is hot, add the chiles. Stir them continually so they cook evenly until they are soft, 5 to 10 minutes. Add the onion and garlic and continue to stir lightly about 5 minutes more, enough to soften them and infuse the oil with their flavor. Add the tomato and cook just until warm, about 3 minutes more.
Remove the pan from the heat and put its contents in a blender or food processor. Add the lime juice and cilantro and blend until smooth. If the consistency stays lumpier than you would like, add water as needed. Season with salt and pepper and blend a little longer.
If you like a very smooth salsa, you can strain the mixture through a fine-mesh sieve at this point.
Let the salsa cool to room temperature. Serve immediately or store in the fridge for up to 1 week