Preheat your broiler for about 10 minutes.
Lay out your tomatoes, jalapeños, and chilies on a baking sheet lined with aluminum foil. Broil for about 10 minutes and check for black char marks. These are good! If the tops are well-charred, it’s time to turn. Char tomatoes, peppers, and chilies on all sides -- removing the jalapeños and chilies if you have to, in order to ensure the tomatoes get really dark and toasty.
Rest the tomatoes, peppers, and chilies until they’re cool enough to handle. Peel off the black skin of the peppers and tomatoes and remove the stems.
Mash the chilies, lime, a heavy pinch of sea salt, and garlic with the back of a fork. Add in the tomatoes and mash with the tomato, err, potato masher until you reach your desired consistency. Add onion and cilantro and stir. Season with salt and pepper to taste.