After about 30 minutes of roasting, pour the tomato mix & sliced onions into the pan, put rest of seasoning paste onto the meat, and add about 1-1 1/2 liters of water.
cover tightly with aluminum foil, and another lid or pan (dutch ovens would be perfect).
Roast for about 6 hours at 250 degrees. Open 2 or 3 times to baste it in it's own juices. Serve with rice is totally optional.