Meatballs tajine with bell pepper and potatoes

http://madeinmorocco.net/cuisine/recipes

Ingredients * For the meatballs: 300g ground lamb or beef * 1 pinch salt * 1 pinch cumin * 1 pinch black pepper * Other ingredients: 1 sweet pepper * 2 potatoes * 4 tablespoons olive oil * 1 onion * 2 pinches salt * 1 pinch black pepper * 1 pinch cumin * 1 pinch ginger * 1 teaspoon dried coriander * 2 teaspoons tomato sauce * olives for decoration