1Cook Brussels sprouts in a covered pan with about 1/3 cup of salted water for about 10 minutes. Until crisp-tender not overly soft.
2In a saucepan, cook onion and butter until the onion is tender but not brown. Lower heat. Mix in flour, brown sugar, mustard, and 1 tsp salt. Stir in milk, stirring constantly, till thickened. Blend in sour cream. Add Brussels sprouts