Curried vegetable burgers (vegetarian)

Name: Curried vegetable burgers (vegetarian)
Prep time: 20 min
Cook time: 20 min
Total time: 40 min
Cuisine: Indian
Ingredients: 2 tablespoons olive oil; 1 onion, finely chopped; 1 garlic clove, crushed; 2 zucchinis, grated; 1 large carrot, grated; 100g (about 4 slices) wholemeal bread, crusts removed; 400g canned chickpeas, rinsed, drained; 3 teaspoons mild curry paste; 3 tablespoons crunchy peanut butter; 1 egg yolk; 3 tablespoons chopped coriander leaves, plus extra leaves to serve; 6 bread rolls (we used cape seed); Mayonnaise, to serve; Chutney, to serve; Lettuce, to serve; Tomato, to serve