Place the carrot, onion, leek, celery and shanks into a large stockpot. Throw in the peppercorns and season with salt to taste. Add enough water to the pot to cover the vegetables. Cover and cook over medium heat for 2 to 3 hours, or until everything is tender. Remove the shanks from the water and drain. Reserve vegetables and cooking liquid.
Preheat the oven to 220 degrees C. Melt the margarine in an enamel coated cast iron baking dish. Place the drained shanks, cooked vegetables and about 2 cups of the cooking liquid into the pan.
Bake for 30 minutes in the preheated oven. During the last 10 minutes, sprinkle with beer in which a good amount of salt has been dissolved. Dust lightly with cumin to increase flavour. Serve with potato or white bread dumplings, or sauerkraut salad.