Preheat oven to 350°F. Line a rimmed baking sheet with parchment, and place tomatoes, bell peppers, and garlic on it. Roast in the oven until tomatoes are wrinkled and lightly charred in spots and garlic is soft, about 1 hour. Let cool and remove skin from the tomatoes and peppers, and peel the garlic.

In a blender or food processor, combine everything but the olive oil. Once the ingredients are mostly blended, start drizzling in the olive oil while running the blender. Blend until you reach your desired consistency.