Giant Stuffed Sandwich

Ingredients

• 1/2 cup quick-cooking oats, uncooked
• 1/2 cup boiling water
• 2 tablespoons butter
• 1 16-oz. pkg. hot roll mix
• 3/4 cup very warm water (110 to 115 degrees)
• 2 eggs, beaten
• 1/2 cup mayonnaise
• 1/4 cup coarse mustard
• 1 9-oz. pkg. sliced deli honey ham
• 1 6-oz. pkg. sliced deli roast turkey
• 1 6-oz. pkg. sliced deli roast chicken
• 1 to 2 tomatoes, thinly sliced
• 1 red onion, thinly sliced
• 8 slices Cheddar cheese
• Garnish: shredded lettuce