Place brisket in a large stockpot; add water and next 5 ingredients (water through garlic). Bring to a boil. Cover, reduce heat, and simmer 3 hours. Remove brisket from pot.
Place brisket on the rack of a broiler pan or roasting pan coated with cooking spray; place rack in pan. Strain cooking liquid through a colander into 2 large bowls; discard solids. Return liquid to pot. Add caraway seeds and cabbage; bring to a boil. Reduce heat; simmer 20 minutes. Drain.
While cabbage is cooking, place potatoes in a large Dutch oven. Cover with water. Bring to a boil; cook 20 minutes or until tender. Drain. Return potatoes to pan. Stir in parsley, butter, rind, juice, and pepper; toss to coat.
Combine breadcrumbs and horseradish. Spread mustard over one side of brisket. Press breadcrumb mixture onto mustard. Broil 3 minutes or until lightly browned. Serve brisket with cabbage and potatoes.