Buffalo Cauliflower Pita Pockets

Name: Buffalo Cauliflower Pita Pockets
Cuisine: American
Ingredients: 2 15-oz. cans no-salt-added chickpeas; 2 tablespoons white wine vinegar; 1 tablespoon Dijon mustard; 1 to 2 tablespoons hot sauce; 1 tablespoon no-salt-added tomato paste; 1 12- to 16-oz. package frozen cauliflower, large florets cut into bite-size pieces; ½ cup chopped onion; ½ cup chopped carrot; 3 cloves garlic, minced; Freshly ground black pepper, to taste; 8 lettuce leaves; 4 whole wheat pita bread rounds, halved crosswise and warmed; ½ cup finely chopped celery; Lemon wedges