Start by cutting your carrots, leeks, red onions, and lemon.  Put it in a small deep dish, and add the parsley.  Place your veal shank on top of your vegetables in the dish. Add your beer to your dish.  Put the lid on the dish and place it in the oven at 150 degrees Celsius (302 degrees Fahrenheit) for 5 hours. After 5 hours, take out the veal shank. Pour the liquid into a saucepan. Thicken the liquid and add a bit of coloring if desired, and you have the sauce. When the sauce is ready, serve your veal shank with your side dishes.