4 medium sized tomatoes
1 yellow onion
6 cloves garlic, peeled
3 chili peppers, your choice for heat control
¼ cup vegetable oil
2 teaspoons salt
1 teaspoon cumin
¼ cup cilantro leaves
2 tablespoons fresh lime juice
Preheat the broiler and set an oven rack about 5 inches beneath the heating element. Line a rimmed baking sheet with aluminum foil.
Place the tomatoes, onions, garlic, whole serrano chile peppers and vegetable oil directly on the prepared baking sheet and toss with your hands. Broil until softened and charred, 10-15 minutes.
Transfer the vegetables and juices to a food processor fitted with the metal blade.
Add the salt and cumin and pulse until just slightly chunky.
Add the cilantro and fresh lime juice, and pulse until the cilantro is chopped. Taste and adjust the seasoning with salt and more lime juice if necessary.