Mix the soy sauce, mustard, lemon juice and spices in a bowl. Stir well and pour it over the chicken legs. Roll them well in the marinade and leave in the fridge for a few hours.
Arrange them in a buttered oven dish. Pour in a little water and cover them with foil.
Bake at 392°F (200 °C) for about 1 hour. Baste them from time to time with the remaining marinade.
Finally, remove the foil and bake until golden. Sprinkle with sesame seeds and stir well.
Return the oven dish to the oven for a few more min. just to lightly toast the sesame seeds.