Chickpea and tuna salad

Name: Chickpea and tuna salad
Cuisine: World Cuisine
Ingredients: grated zest half a lemon; pinch black pepper; 20ml extra-virgin olive oil; 1 small red onion, finely chopped; 180g ripe cherry tomatoes, cut into quarters; 8cm cucumber, chopped; 1 x 400g tin chickpeas in water, drained (drained weight 240g); 1 x 200g tin tuna in water, drained (drained weight 150g); 150g salad leaves/lettuce; 2 lemon wedges