Clean and slice the carrots and leek. Peel and quarter the onions. Put aside.
Heat the fat in a roaster. Put the meat in and sear it properly on all sides so that the meat gets color, then remove it. Put the vegetables in the roasting pan and toast them with a little tomato paste. When the vegetables have gotten their color, add the meat again and fill the whole roasting pan with enough water to cover about 3/4 of the meat. Add salt, pepper and paprika powder, put the lid on and let everything boil gently. Turn the meat every 45 minutes. After about 4-5 hours the meat should almost fall off the bone.
Remove the meat, season the sauce to taste and, if necessary, season again and thicken with a sauce thickener.
Roasted potatoes from the oven and beans go well with this.