Chicken gyro salad with pittas

Name: Chicken gyro salad with pittas
Prep time: 5 min
Cook time: 30 min
Total time: 35 min
Cuisine: European, Greek, Mediterranean
Ingredients: 300g fat-free natural Greek yogurt; 1 tsp lemon juice; 2 tbsp red wine vinegar; 6 garlic cloves, crushed; 2 tsp ground cumin; 1 tsp dried oregano; 2 tsp sweet paprika; ½ tsp ground cinnamon; 8 large skinless and boneless chicken thighs, visible fat removed; 2 small red onions, halved and thinly sliced; 4 tomatoes, deseeded and thinly sliced; 1 tsp sumac; ½ medium cucumber, peeled and coarsely grated; 2 tbsp chopped fresh dill; 4 little gem lettuces, shredded; 4 x 60g wholemeal pitta breads, toasted