Stir and pour this mixture over the meat and potatoes. Rub this mixture into the meat and potatoes, in order to season them well.
Take a baking bag, place the meat in it carefully, add the potatoes and pour in any remaining marinade from the tray. Tie the bag, put it in a clean tray and place in the oven. Bake the meat at 320°F (160 °C) for 1 1/2 hours, then open the bag, turn the oven up to 356°F (180 °C) and bake for another 30 min.