Chicken tikka burgers

Name: Chicken tikka burgers
Prep time: 20 min
Cook time: 15 min
Total time: 35 min
Cuisine: Indian
Ingredients: 6 small chicken breasts; 6 burger buns (we used ciabatta); 2 tbsp tomato purée; 200g pot Greek yogurt; thumb-sized piece ginger very finely grated; 4 garlic cloves very finely grated or crushed; 2 tbsp garam masala; ½ tsp ground cinnamon; ½ tsp ground cayenne pepper; juice 1 lemon plus wedges to serve; 2 tomatoes chopped; 1 small red onion chopped; 1 green chilli chopped; 1 tsp tamarind pulp; 2 tbsp tomato ketchup; ½ cucumber sliced; 1 Little Gem lettuce shredded; small bunch mint leaves picked; 1 small red onion halved and finely sliced