• Preheat the broiler, with the rack 2 to 3 inches from the heat source. Put the tomatoes, garlic cloves, and onion on a baking sheet lined with foil and broil, turning the vegetables halfway through, until they are charred and the tomatoes are mushy, 5 to 7 minutes for the garlic, and 10 to 12 minutes for the other vegetables. Remove the garlic when charred and softened and when it is cool enough to handle, peel it. Alternatively, you can toast the vegetables on a hot comal or skillet over medium heat, turning them every 4 to 5 minutes, until charred and soft. Transfer the tomatoes, onion, and garlic to a blender, along with any juices on the baking sheet.
• Set a comal or small skillet over medium-low heat. Add the chipotles and peanuts and toast, stirring the peanuts and turning the chiles from time to time, just until the chiles soften, puff, and begin to lightly toast but not burn, 4 to 5 minutes. The peanuts should be slightly toasted, but that will barely show. Transfer to the blender.
• Toast the oregano on the hot pan for 10 to 15 seconds, until fragrant and just beginning to darken, and add to the blender.
• Add the vinegar, water, and salt to the blender and puree until smooth. Taste and adjust the salt.
• The salsa will keep, tightly covered, for up to 5 days in the refrigerator. Stir well before using.

Notes:

• You can substitute 1 (15-ounce) can fire-roasted tomatoes for the roasted fresh tomatoes. Add them to the blender along with the roasted onion and garlic.
• If you can only find salted and roasted peanuts, toast them with the chipotles as directed in the recipe, but reduce the salt in the recipe to 1⁄2 teaspoon, then season to taste with more salt if necessary.