Prepare the meat by cutting into large chunks. You can also slice it very thinly while slightly frozen (slicing against the grain) if you'd rather skip the shredding step later on.

Layer the onions on the bottom of the Crockpot and toss in the meat.

Mix together the sauce, water, mustard, vinegar, and spices and pour over onions and meat.

Cook on low for four hours. (For best results, shred meat at hour three and continue cooking for the final hour. If not possible, shred the meat just before eating.) Ladle on top of rice or Kaiser rolls and enjoy!