Rinse the chickpeas in cold water and leave to drain. Core and deseed the peppers and cut the flesh into 2 cm (¾ inch) strips. Cut the onion in half and then cut each half into quarters, leaving the root on so the wedges stay together
Drizzle the peppers, onions and tomatoes with olive oil and salt and pepper. Heat a griddle pan over a high heat and cook the peppers for 2 minutes on each side. Slice the peppers and place in an ovenproof dish and cook the onion in the same way. Place the onion and tomatoes with the peppers, sprinkle with fennel seeds and cook in a preheated oven, 180°C (350°F), Gas Mark 4, for 20 minutes until done.
Meanwhile, make the dressing. Whisk together the vinegar and oil with the crushed garlic and cumin.
Transfer the drained chickpeas to a large salad bowl and mix in the hot vegetables and chopped parsley. Season to taste with salt and pepper, drizzle over the dressing and stir to combine. Serve with a dollop of tzatziki, if liked (see below).