Preheat oven to 325°. In a large, oven safe pot, boil corned beef in water and 2 bottles of beer along with garlic and cracked peppercorns over medium heat for 1 hour.
Skim off fat and add remaining beer. Place pot in oven and cook for 2 hours.
Clean and rinse brussels sprouts. Cook sprouts in chicken stock until slightly firm. Remove from stock and set aside, saving the stock. Crack the green peppercorns in a mortar or by hand (never in a grinder as they are quite soft). In a saucepan, cook shallots in olive oil over medium heat. Add in green peppercorns and toss. Add in one cup of the stock and reduce. Add in butter to finish sauce. Strain sauce if desired.
Dutch Oven Version: Set Dutch oven on low. Pour in water, beer, cracked Muntok & Tellicherry peppercorn and garlic along with corned beef and cook for 8 hours, skimming fat occasionally. |