Makes 4 cups
4 large tomatoes, roasted until blistered (see note)
half of a medium white onion, chopped
2 to 4 serrano chiles, roasted until blistered, and chopped (see note)
1 garlic clove, chopped
sea salt to taste
1 tablespoon vegetable oil
Combine all sauce ingredients except the oil in a molcajete or food processor and puree. In a heavy, 12-inch skillet, heat the oil over medium heat. Add the tomato mixture (be careful – it will splatter), reduce heat to low, and cook for about 5 minutes. Keep warm.
Notes:
Tomatoes – Native to the New World, tomatoes are an important ingredient in many Mexican dishes and are prepared in a variety of ways. For recipes that call for peeled tomatoes, bring a pot of water to a boil, cut an X in the bottom of each tomato, and gently slide them into the boiling water. Boil for up to 1 minutes and transfer to a colander. When the tomatoes are cool enough to handle, gently peel away the skin and discard it.
Roasting can be done under a broiler or on a comal, but the broiler is faster and creates less mess. Place tomatoes on a rimmed baking sheet and broil directly under the heat source for 3 minutes. Using tongs, turn tomatoes and broil an additional 3 minutes, or until the tomatoes are blistered all over. Remove from the heat and peel or not, according to the recipe.
Fresh Chiles – Jalapenos are probably the most recognizable Mexican chile and the easiest to find in the United States. The jalapeno is a fat, bullet-shaped, deep green chile, two to three inches long. In sauces, jalapenos can be substituted for serranos. The poblano is dark green, five to six inches long, and triangular in shape, with a wide stem end. Strips of roasted poblanos are made in rajas and are the basis for many chile relleno dishes. Serranos are thin, bullet-shaped chiles, dark green in color and two to three inches in length. Raw or roasted serranos add heat and flavor to many sauces.
Fresh chiles can be roasted until charred and blistered on a dry comal, under a broiler, or over an open flame, using tongs. For rajas and rellenos, put charred poblano chiles in a plastic bag and allow them to sweat for 10 to 15 minutes. Using rubber gloves, peel off the charred outer skin. (Do not peel chiles under running water or much of the roasted flavor will be lost.) For rellenos, cut a slit down one side from shoulder to the tip and scrape out the seeds and membranes, being careful to keep the chile as intact as possible. For rajas, cut off the stem end and slice the peppers lengthwise into thin, 1/4-inch strips. (Don’t rub your eyes, nose, mouth, or other tender body areas while handling chiles. Capsaicin, the volatile substance that gives chiles their pungency, is stored in the seeds and membranes and will burn the skin.)