Make a marinade from the wine, mustard, soya sauce, pressed garlic, some black pepper and a few drops of oil. Brush the turkey legs well with it and let them marinate for 1 hour, turning them over frequently.
Peel the potatoes and cut them into a greased tray. Fry the onions with a little oil and mix into the potatoes.
Add salt and spices to taste. Place the turkey legs between the potatoes and pour the remaining marinade on top.
Place a sheet of foil and put the dish to bake in a preheated oven at 392°F (200 °C).