How to Make It
Preheat oven to 450°F. Line a baking sheet with parchment paper, and spread tomatoes, onion, jalapeños, and garlic in a single layer on parchment. Roast in preheated oven until onions and garlic are charred and soft, 15 to 20 minutes. Remove onion and garlic to a plate, and roast tomatoes and jalapeños an additional 15 to 20 minutes, until charred and soft.
Remove jalapeño stems. Process tomatoes, onion, jalapeños, garlic, cilantro, chipotle, and salt in a blender until smooth. With blender running, slowly pour oil through lid or food chute, followed by lime juice, processing until thoroughly combined. (If salsa is too thick, add water, 1 tablespoon at a time, to reach desired consistency.) Add more salt and chipotle, if desired. Cover and chill until ready to serve.