Greek Salad Sandwich from Everyday Food

• 1 cup canned chickpeas, rinsed and drained
• 2 tablespoons fresh lemon juice
• 2 tablespoons plus 2 teaspoons extra-virgin olive oil
• 1/4 cup fresh parsley leaves
• 1/2 small red onion, thinly sliced
• Coarse salt and ground pepper
• 3 ounces crumbled feta
• 8 slices rustic bread or olive bread
• 1/2 medium cucumber, thinly sliced
• 1 tomato, thinly sliced