Copycat In-N-Out Double-Double Animal-Style Burger

Ingredients: (makes four double burgers)

• 1/2 cup mayonnaise

• 1 1/2 tablespoons ketchup

• 1 tablespoon pickle relish

• 1 teaspoon sugar

• 3/4 teaspoon white vinegar

• 1 tablespoon butter

• 1 tablespoon canola oil

• 3 cups finely chopped yellow onions

• 3/4 teaspoons salt, divided

• 4 tablespoons water, or as needed

• 2 - 4 cloves of garlic minced (optional)

• 1 teaspoon Worcestershire sauce (optional)

• 1 lb ground chuck or 80% lean ground beef

• 1 teaspoon canola oil

• 1/2 teaspoon black pepper

• 3 tablespoons mustard

• 8 slices American cheese

• 4 hamburger buns, toasted (potato buns work great here)

• 16 dill pickle chips

• 4 slices tomato

• 2 leaves iceberg lettuce, torn

Directions

• Stir together mayonnaise, ketchup, relish, sugar, and vinegar in a small bowl for the sauce.

• Heat butter and one tablespoon of oil in a nonstick skillet over medium heat. Add onions and season with ¼ teaspoon salt. Cook, stirring occasionally, until onions are tender and golden brown for about 20 minutes. 

• When the skillet starts to dry, add one tablespoon of water. 

• Continue cooking, stirring often, adding more water as needed, one tablespoon at a time, until onions are very soft, deeply browned, and jammy, 10 to 15 minutes more. You may not need to use all the water. (Note:  If garlic and Worcestershire sauce are added to the onions, add them in the last 1-3 minutes of caramelizing the onions).  Remove from heat.

• Shape beef into 8 patties, about 3/8-inch-thick and 4 inches in diameter. Sprinkle with pepper and remaining 1/2 teaspoon salt.

• Heat 1 teaspoon oil in a large cast-iron skillet over medium-high heat. Working in batches as needed, add patties to skillet. 

• Spread two teaspoons of mustard over top of each patty. 

• Cook until browned, about 2 minutes per side. 

• Top patties with cheese and onions. 

• Cook, covered, for about 30 seconds until cheese is melted. An instant-read thermometer inserted into the center should read at least 160 degrees F (70 degrees C). 

• Layer patties to create four stacks.

• Spread sauce onto bun bottoms. Fill each bun with four pickles, a tomato slice, lettuce, and one patty stack.