Rinse the chicken, salt, pepper and season to taste, pour kefir and mix well. Leave on for 30 minutes.
Peel and dice the potatoes, salt, pepper and add the chopped garlic, pour a few tablespoons of oil and mix.
Put the potatoes in a greased baking dish. Spread coarsely chopped tomatoes on top.
Lay the meat on top and pour the remaining sauce.
Bake at 200 degrees for 40-55 minutes.