Remove seeds from peppers. Place peppers in a saucepan with boiling water to cover; let stand 30 minutes. Drain. Peel and coarsely chop peppers.
Bake tomato halves in a roasting pan coated with cooking spray at 450° for 20 minutes or until blackened.
Sauté garlic and onion in hot oil 3 minutes or until tender.
Pulse chopped pepper, tomato halves, onion mixture, salt, and cumin in a food processor until chunky; stir in cilantro. Garnish, if desired.