1- First of all, put your all ingredients on the work-table. Then, finely chopped steaks into Julienne. Put the meats into deep bowl. Now, your meats are ready to marinate.
2- For marinate meat: Put finely choped onion, garlic, vinegar, olive oil, thyme and cumin onto the meats. Then mix them. Cover the bowl, stretch it and rest for a few hours in the fridge (at least 1 hour). Then prepare your tomato sauce.
3- For tomato sauce: Put olive oil into a pan. Then, add tomato paste onto olive oil and cook mixture until 2-3 minutes. Then, put grated tomatoes onto mixture and cook it until 5-7 minutes. Then, add grated garlic and sprinkle salt onto tomato sauce and stir. Then remove it from heat.
4- Then, pour your vegetable oil into a large pan and heat the oil. Put meats into pan, cook the meats until the their water disappears. Pour hot water if needed and cook until your meat is soft. Then, sprinkle salt and spices if needed (thyme, red pepper flakes, ground black pepper). Cook your meats 1-3 minutes.
5- Meanwhile, peel the potatoes and wash and drain. Then, chop your potatoes to thickness of matchstick (we mean that chop the potatoes as thin as possible. Bye the way our potatoes sticks were abit thick in this recipe). Put a small amount of vegetable oil in a large pan and heat. Then, put the potato into heated oil and cook them until golden brown on both sides. Don't forget to prepare garlic-yogurt sauce.
6- For garlic-yogurt sauce: Combine your plain yogurt, crushed garlic and salt in a bowl and mix them well.
7- For serving Çökertme Kebabı: Transfer your fried potatoes in serving plates, then pour garlic-yogurt sauce onto top, finally put tomato sauce and cooked meats onto. Serve hot.