Preheat oven to 425 F.
Roughly chop the tomatoes, onion and peppers. Serranos can be spicy, so if you prefer no spice, leave them out.
Lay them out on a baking sheet. Drizzle a bit of neutral oil, and salt and pepper. Toss to coat them thoroughly. Spread them in a single layer.
Roast the veggies in the oven for 30 minutes. When they are done, let them cool for about 5 minutes.
Blend the veggies in a blender or food processor until they become a chunky salsa. Add water or broth as needed to thin it out.
Heat up a little oil in a pan and then fry the minced garlic for 1 minute, careful, not to burn it. Then add in the salsa along with the cumin, oregano and chipotles in adobo (if using). Taste and adjust for final seasoning and keep warm on low.