This is a famous Greek delicacy. Lots of recipes are available out there on web. I tentatively followed instructions given in an app on Sanjeev Kapoor’s (Indian Celebrity Chef) recipes. Here you go if you want to try it.
Take boneless chicken leg meat of around 250 grams and mix 2 tbsp of thick yogurt, around 1.5 tsp of garlic paste, 1 tsp of lemon juice, 1 tbsp of olive oil, 0.75 tsp of fresh oregano, salt and crushed black pepper together in a bowl and marinate for 1-2 hours. Fit in bamboo skewers, brush oil, grill and serve hot.