Roast beef and brie sandwiches

1. Saute first 3 ingredients in a medium nonstick skillet over medium-high heat 8 minutes or until onion is tender.

2. Brush cut sides of rolls evenly with melted butter, and cook, buttered side down, in a skillet or on a griddle over medium heat, 5 minutes or until lightly browned. Turn roll halves over in skillet; layer cut sides of bottom halves evenly with Brie slices, onion mixture, and roast beef. Remove rolls from skillet.

3. Spread 1 tablespoon Horseradish sauce on cut side of each top half, and place, sauce side down, on top of roast beef.

4. Serve sandwiches with remaining sauce.