Greek Chicken Gyros with Tzatziki

500g chicken thigh fillets, bone out

For the marinade:

1 tbsp olive oil

3 tbsp full-fat Greek yoghurt

1 heaped tbsp dried oregano

1 tsp dried mint

zest of 1 lemon

Juice of one lemon

Salt and pepper

To serve:

Pitta bread

Chopped tomatoes, cucumber, olives and onion

Tzatziki