"No-Tuna" Salad Sandwich

Name: "No-Tuna" Salad Sandwich
Cuisine: American
Ingredients: 1 (15-ounce) can chickpeas, rinsed and drained (1½ cups); 3 tablespoons tahini; 1 teaspoon Dijon or spicy brown mustard; 1 tablespoon maple syrup or agave nectar; ¼ cup diced red onion; ¼ cup diced celery; ¼ cup diced pickle; 1 teaspoon capers, drained and loosely chopped; Healthy pinch each sea salt and black pepper; 1 tablespoon roasted unsalted sunflower seeds (optional); 8 slices whole-wheat bread; Dijon or spicy brown mustard; Romaine lettuce; Tomato, sliced; Red onion, sliced