Line a large skillet with aluminum foil and heat on medium-high heat. Or roast on a grill.
1 pound tomatoes (about 3 medium), 1 small serrano pepper (optional for extra heat)
Place the tomatoes and serrano pepper. Roast until all sides have blackened and the tomatoes are cooked. Keep turning to cook all sides. About 20 minutes total.
Note: If the pepper gets roasted faster than the tomatoes, remove and set aside. Remove the stem from the serrano pepper and keep the seeds.
Meanwhile, in a small saucepan, add two cups of water, the chiles morita, onion and garlic. Cook over medium-high heat until it boils. Remove from heat and set aside to hydrate the chile until the tomatoes are cooked through.
3 morita chiles, ½ medium white onion, 1 large garlic clove
In a blender or food processor, puree the tomatoes, serrano, chile morita peppers, onion, garlic, sugar, white vinegar, salt and pepper until smooth.
¼ teaspoon sugar, 1 tablespoon white vinegar, 1 teaspoon kosher or sea salt, ½ teaspoon freshly ground black pepper
Note: If the salsa is too dense to blend, add ¼ cup water from where the chiles were cooked.
Transfer to a bowl and taste. Add more salt and pepper if needed according to taste.