Cut bell peppers in half lengthwise; discard seeds and membranes. Place pepper halves, skin sides up, on a foil-lined baking sheet; flatten with hand. Arrange onion and garlic around peppers on baking sheet. Broil 10 minutes or until blackened. Place in a zip-top plastic bag; seal. Let stand 15 minutes; peel.
Place peppers, onion, and garlic in a food processor; process until finely chopped. Add remaining ingredients; process until smooth. Serve with toasted pita triangles.