This is the perfect make-ahead sandwich. Simply prepare it a day in advance, cover with plastic wrap, and keep it in your refrigerator. Toss it in your lunch bag with a piece of fruit for a simple lunch on the go!
3 tablespoons fat-free mayonnaise
1 tablespoon stone-ground mustard
2 teaspoons prepared horseradish
8 (1-ounce) slices reduced-calorie rye bread
2 cups loosely packed fresh baby spinach
1 0 ounces thinly sliced deli roast beef
4 slices red onion, separated into rings
How to Make It
Combine first 3 ingredients, stirring well. Spread mixture evenly over 1 side of each bread slice. Top half of bread with spinach, beef, and onion. Top with remaining bread slices. Cut sandwiches in half to serve.