- Preheat oven to 425 degrees. Toss tomatoes and peppers in oil and place on cookie sheet. Roast in oven, turning once, until skin blisters and separates, about 20-25 minutes. Set aside to cool.
- Place onion and garlic in a food processor and pulse until finely chopped.
- Remove skins from peppers and tomatoes. Add serrano peppers to food processor with half of the cilantro and pulse four times.
- Add tomatoes and salt, pulse four times. Garnish with remaining cilantro leaves and serve.