Wash the turkey legs and dry them. Then sprinkle salt and black pepper over them. Smear them well with the marinade and leave them as is for at least 2 hours.
Clean the onions and carrots and cut them into slices. Do the same with the mushrooms (personally I peel them and don't wash them). Cut the peeled potatoes into coarse pieces. Mix all of the prepared veggies in a clay pot.
Sprinkle salt and black pepper over them. Pour in a little oil and 1/2 cup water. Place the marinated legs in the middle. If there's any marinade left, pour it over the legs.
Cover the clay pot and put it in a cold oven. Bake at 428°F (220 °C) for 30 min., then lower the heat to 356°F (180 °C). Bake another 2 hours or so.