Bring the water, butter, salt and Brussels sprouts to a boil in a Dutch oven or a large deep skillet. Cover and steam over medium-heat until the Brussels sprouts are brightly colored and just tender, 5 to 10 minutes.
Remove the lid and continue to cook until the liquid evaporates, 1 to 2 minutes longer. Saute to intensify flavors, 1 to 2 minutes longer. Adjust seasonings, including pepper to taste, and serve.
Remove Brussels sprouts from pan. Add mustard to remaining liquid in pan. Stir and make sauce.
Pour over Brussels sprouts.
Recipe courtesy of Pam Anderson