Cheddar on Rye Smash Burger from Smashed: 60 Epic Smash Burgers and Sandwiches for Dinner, for Lunch

Ingredients

• 1 tablespoon (14 g) unsalted butter
• 2 slices rye bread
• 6–7 ounces (170 to 200 g) 80/20 ground beef, divided into two 3- to 3½-ounce (85 to 100 g) loosely packed meatballs
• 1 tablespoon (15 ml) vegetable oil
• 2 teaspoons salt (to taste)
• 2 slices cheddar cheese
• 2 teaspoons pepper (to taste)
• Mayonnaise, for topping
• Mustard, for topping
• Shredded lettuce, for topping
• 4 dill pickle chips
• 1 tomato, sliced
• ½ red onion, thinly sliced