Spike the shanks with garlic in several spots. Rub them with black pepper, paprika and salt. Put them in a deep oven dish and pour on the beer, a little water whipped with the mustard, the soya sauce, the allspice and 2-3 pinches of cumin.
Bake at 392°F (200 °C) for about 2 hours, having covered the oven dish with foil and during baking, turn the shanks over once. Finally, remove the foil and bake to a brown and crispy crust for about 15 minutes, if desired.