Roast the tomatoes, jalapeños, onion and garlic in a pan until the tomatoes and jalapeños begin to bubble and blacken. Turn and roast all sides. (You can also do this in the oven under the broiler.)
Add the tomatoes, onion, garlic, chipotle, salt and oil to a blender or food processor. Cut the stems from the jalapeños and add them to the blender as well. Blend until smooth, or until desired consistency.
Serve warm or refrigerate until ready to serve.
Storage: Once fully cooled, refrigerate any leftovers in an airtight container or jar for up to 5 days. You can also leave it in the serving bowl if you cover it tightly with foil. You don't need to reheat this recipe. It's best served straight out of the fridge or at room temperature. More Heat: If you want your salsa really spicy, leave the seeds in the jalapeños. If you want to quadruple the heat, swap the jalapeños for serrano peppers instead. Less Heat: If you want less heat, make sure to remove all seeds and membranes from the peppers. You can also only use half of the jalapenos for a milder salsa.