6 cups water
2 cups lager beer
1 ½ cups coarse salt
1 cup (packed) golden brown sugar
¼ cup pickling spices
1 6-to-8-pound flat cut beef brisket, trimmed, with some fat remaining
Corned beef and vegetables
1 1/2 –ounce bottle Guinness stout or other stour or porter
4 bay leaves
1 tablespoon coriander seeds
2 whole allspice
1 dried chile de arbol, **broken in half
3 medium turnips, peeled, quartered
8 unpeeled medium white-skinned or red-skinned potatoes (about 3 pounds)
6 medium carrots, peeled
4 medium onions, peeled, halved through root ends
2 medium parsnips, peeled, cut into 2-inch lengths
1 2-pound head of cabbage, quartered
Pour 6 cups water and beer into large deep roasting pan. Add coarse salt; stir until dissolved. Add sugar; stir until dissolved. If desired, mix in pickling spices. Pierce brisket all over with tip of small knife. Submerge brisket in liquid, then top with heavy platter to weight down. Cover and refrigerate 4 days. Remove brisket from brine. Rinse with cold running water. Can be made 2 days ahead. Wrap corned beef in plastic, cover with foil and refrigerate.
Place corned beef in very large wide pot. Add stout and enough water to cover by 1 inch. Wrap cheesecloth around bay leaves, coriander seeds, allspice, and chile, enclosing completely, and tie with kitchen string to secure. Add spice bag to pot with beef bring to boil. Reduce heat to medium-low, cover, and simmer until beef is tender, about 2 ¼ hours. Transfer beef to large baking sheet.
Add turnips and all remaining vegetables to liquid in pot; bring to boil. Reduce heat to medium and boil gently until all vegetables are tender, about 25 minutes. Using slotted spoon, transfer vegetables to baking sheet with beef. Return beef to pot and rewarm 5 minutes. Discard spice bag.
Cut beef against grain into ¼-inch thick slices. Arrange beef and vegetables on platter.
Serve with Horseradish Cream and Guinness Mustard.