Foryoueats: Smash Burger Taco

Ingredients

• 1/4 cup mayonnaise
• 1 tablespoon ketchup
• 1 teaspoon mustard
• 1 tablespoon relish
• 1/2 teaspoon hot sauce
• 1 lb ground round
• 1 teaspoon Kosher salt
• 1/2 teaspoon freshly ground black pepper
• 4 (6-inch) flour tortillas
• 2 slices American cheese, cut in half lengthwise
• 1 cup shredded iceberg lettuce
• 1/4 cup diced onion