Step 1

Cut sausage into 3 pieces, then cut each piece lengthwise in half. Cook in large nonstick skillet on medium heat 5 to 7 min. or until evenly browned, turning occasionally. Remove from skillet; cover to keep warm.

Step 2

Melt butter in skillet. Add onions; cook 3 min. or until tender, stirring frequently. Stir in mustard. Add sauerkraut; mix lightly. Cook 5 min., stirring occasionally.

Step 3

Top with sausage; cover. Cook 5 min. or until heated through.