PREPARATION:

1. Place butter and caraway in 1- to 2-quart saucepan. Cook over medium heat until butter is melted. Mix in hollandaise mix with wire whisk. While whisking, slowly add water according to package directions. Add mustard and ground red pepper; whisk until bubbly. Simmer and stir 1 minute or until thickened; set aside.
2. Preheat broiler. Place bread on baking sheet. Broil 4 inches from heat 1-1/2 to 2 minutes per side or until crisp; set aside. Place pastrami on plate; cover with plastic wrap. Microwave on HIGH 1 minute or until heated through; set aside. Place sauerkraut in small bowl. Cover with plastic wrap and microwave on HIGH 1 minute or until heated through; set aside.
3. Spread 2 to 3 teaspoons sauce on each slice of toast. Place pastrami on toast; top with sauerkraut. Drizzle each serving with about 1 tablespoon sauce. Lay 2 pepper rings on sauerkraut; top with cheese. Sprinkle with paprika or ground red pepper, if desired. Broil 2 to 3 minutes or until cheese bubbles. Serve with remaining sauce to spoon over individual servings.