MAKES 4 CUPS

9 plum tomatoes, cut into 1/2-inch pieces
1 large white onion, peeled and quartered
1 serrano chilies, plus more if desired
1 poblano pepper
2 garlic cloves, unpeeled
Coarse salt

Preheat broiler. Place tomatoes, onion, peppers, and garlic on a rimmed baking sheet. Broil until tomatoes and peppers are charred, about 7 minutes. Let stand until cool enough to handle.

Peel the roasted garlic. Transfer to a blender along with the charred tomatoes, onion, peppers, and 1 tablespoon salt. Puree until smooth. For a thinner consistency, add water as needed. Season with salt to taste.