This is a copycat of In-N-Out’s Animal Style cheeseburger — a smash-style beef patty cooked with mustard on the griddle, topped with deeply caramelized onions, extra pickles, American cheese, and a Thousand Island-style spread. It takes more active time than a standard cheeseburger, mostly because the onions need a good 30–40 minutes to go properly jammy, but every component can be made ahead so weeknight assembly is fast.
Why this recipe works
Two things actually move the needle here. First, the mustard-on-the-griddle step: spreading yellow mustard on the raw side of the patty just before the flip lets it hit the hot surface and caramelize rather than steam, adding a sharp, savory crust that plain beef doesn’t get on its own. Second, the onions. Cooking them low and slow — with a splash of water added whenever they threaten to scorch — is what turns sharp raw onion into something sweet and almost jammy. Rush them over high heat and you get soft-but-bitter onion, which throws the whole burger off. Skip the egg in the mix — it makes the patty mushy, and a smash burger needs loose, coarsely packed beef to get those crispy, lacy edges.
Keeping and reheating
Cooked patties keep in an airtight container in the fridge for up to 4 days; caramelized onions keep separately for up to 5 days and actually taste better on day two. The spread holds for a week in the fridge. For longer storage, freeze cooked patties in a single layer on a baking sheet, then transfer to a zip bag — they’re good for up to 3 months. Reheat patties in a dry skillet over medium heat for 2–3 minutes per side until they hit 165°F if you’re reheating from frozen, or just warmed through from the fridge; avoid the microwave since it softens the crust. Warm the onions in the same pan with a teaspoon of water to loosen them up. Toast the bun fresh — it takes 60 seconds and makes a real difference to the final texture.
Troubleshooting
- Patty sticks to the spatula when smashing: The beef is too warm or the spatula isn’t clean and dry. Chill your formed balls for 15 minutes before cooking and press down with a firm, single motion — don’t drag.
- Mustard burns before the patty is cooked through: Your griddle is too hot. Medium-high is the target; if the mustard blackens in under 30 seconds of contact, pull the heat down before the next patty goes on.
- Onions turn out bitter instead of sweet: They cooked too fast. Add a tablespoon of water, drop to low heat, and keep going — they need time, not high temperature, to convert their sugars properly.
- Spread tastes flat: It needs acid. Add a few extra drops of pickle brine or a small squeeze of lemon juice and stir again before serving.
- Bun goes soggy before you finish eating: Spread goes on the bun last, right before assembly, not ahead of time. If you’re prepping for the week, store the spread separately and apply at the moment of serving.
In-N-Out Cheeseburger, Animal Style (Chef’s Copycat)
Ingredients
For the Caramelized Onions:
- 2 cups yellow onions, finely diced (about 2 medium) choose firm, heavy onions for best sweetness
- 1 tbsp neutral oil (canola or grapeseed) high smoke point preferred for griddle work
- ½ tsp kosher salt divide: a pinch for onions; remainder reserved for patties
- 2 tbsp water for deglazing and speeding browning
For the Animal-Style Spread:
- ½ cup mayonnaise full-fat for best texture
- 3 tbsp ketchup a classic brand yields nostalgic flavor
- 2 tbsp sweet pickle relish drain excess liquid for thicker spread
- 1 tsp distilled white vinegar balances sweetness; adjust to taste
- 1 tsp granulated sugar optional; to mimic classic thousand-island sweetness
- ¼ tsp smoked paprika optional; a whisper of smokiness
For the Burgers & Assembly:
- 1 lb ground beef (80/20) cold; divide into four loose 4 oz portions for smashing
- 4 whole sesame seed burger buns soft and squishy for classic texture
- 2 tbsp unsalted butter, softened for toasting buns
- 4 tsp yellow mustard about 1 tsp per patty for mustard-frying
- 4 slices American cheese melts perfectly; do not substitute for true nostalgia
- 4 leaves iceberg lettuce crisp, chilled
- 4 slices ripe tomato cut thick; season lightly with salt if desired
- 16 slices dill pickle chips 4 per burger
- 1 tsp kosher salt for seasoning patties to taste
- ½ tsp freshly ground black pepper to taste
- 1 tsp neutral oil for griddle/pan if needed
Instructions
- Mise en Place (Prep — about 15 minutes): Finely dice the onions; chill lettuce leaves; slice tomatoes. Split buns and lightly butter cut sides. Divide cold ground beef into four loose 4 oz mounds—do not compress. Prepare a square of parchment for each patty to prevent sticking when smashing.
- Caramelize the Onions (Cook — about 18 minutes): Heat a large griddle or heavy skillet over medium to medium-high heat (surface about 350–375°F / 175–190°C). Add 1 tbsp neutral oil, then the diced onions and a pinch of the kosher salt. Cook, stirring every 1–2 minutes, until soft and deep golden-brown. If fond builds up, splash in 1–2 tbsp water to deglaze and continue until jammy and sweet, 15–18 minutes total. Onions should smell sweet and toasty with a mahogany hue.
- Make the Animal-Style Spread (Prep — about 5 minutes, can be done while onions cook): In a bowl, whisk mayonnaise, ketchup, sweet relish, vinegar, sugar, and smoked paprika (if using) until smooth. Taste and adjust acidity/sweetness. Cover and refrigerate so it thickens slightly.
- Toast the Buns (Cook — 1–2 minutes): Wipe the griddle clean if needed; reduce to medium heat (about 350°F / 175°C). Place buttered buns cut-side down and toast until golden at the edges and aromatic, 1–2 minutes. Transfer to plates.
- Smash and Mustard-fry the Patties (Cook — about 5 minutes total): Increase griddle to medium-high to high (about 400°F / 205°C). Lightly oil the surface if dry. Place two beef mounds at a time (or all four if space allows) on the hot surface. Immediately cover each with parchment and press firmly with a heavy spatula or burger press to 1/4-inch thickness—hold pressure for 10–15 seconds for maximum crust. Sprinkle with kosher salt and black pepper. After 60–90 seconds, when edges look lacy and deeply browned and you smell roasted beef, spread about 1 tsp yellow mustard on the raw sides, then flip directly into the mustard. Top each with a slice of American cheese and a generous spoonful of the caramelized onions so they melt into the cheese. Cook 45–75 seconds more until cheese is molten and patty is cooked through but still juicy.Tip: If your pan is small, cook in batches; keep finished patties warm on a low oven (200°F / 95°C) briefly, or tent with foil—do not overhold.
- Assemble the Burgers: Spread 1–1.5 tbsp Animal-Style spread on the bottom buns. Add 4 pickle chips per bun, then a crisp lettuce leaf and a thick tomato slice (season tomato lightly with salt if desired). Crown with the onion-smothered cheeseburger patty. Swipe a thin layer of spread on the top buns, cap the burgers, and serve immediately while the cheese is still glossy and the bun is warm.
Notes
Chef’s Tips:
- Meat Handling: Keep beef cold to maximize crust and juiciness. Loose-packed mounds smash more evenly.
- Smash Technique: Use parchment to prevent sticking and press hard for 10–15 seconds. Don’t move the patty until the crust forms.
- Faster Onions: A tiny pinch (1/16 tsp) of baking soda accelerates browning; add only if needed and taste for balance.
- Mustard Timing: Spread mustard just before the flip so it sizzles into the crust without burning.
- Substitutions: Use American cheese for best melt; if substituting, choose deli-style white American or mild cheddar. Gluten-free buns work well; toast gently. For a lighter option, use 90/10 beef and add a touch more oil to the pan.
- Dietary Swaps: Try a plant-based patty—smash gently and shorten cook time. Use vegan mayo in the spread and dairy-free meltable slices.
Serving Suggestions:
- Plate on a warm, plain white plate to highlight the colors: golden bun, vivid green lettuce, red tomato, and glossy cheese with browned onion. Add a ramekin of extra spread for dipping.
- Pair with crisp shoestring fries or smashed, twice-cooked potatoes. Drinks: a vanilla malt, cold lager, or classic cola.
- Garnish with a few extra caramelized onions and a dill spear for aroma and crunch.
Culinary Context:
This copycat nods to the West Coast burger tradition—thin patties, hot griddle, and a thousand-island style spread—popularized by mid-century drive-ins. The “Animal Style” approach, with mustard-fried patties and a tangle of grilled onions, distills pure Americana with a California accent.Optional Advanced & Parallel Prep:
- Make-ahead: Caramelized onions and spread can be prepared up to 3 days ahead; refrigerate in airtight containers. Rewarm onions gently over low heat with a splash of water.
- Parallel Cooking: Start onions first (longest step), mix the spread during the onion cook, then toast buns and cook patties last.
- Small-kitchen Alternative: Use two pans—one for onions, one for patties—to save time.
Timing
- Prep Time: 15 minutes (0 hours 15 minutes)
- Cook Time: 25 minutes (0 hours 25 minutes)
- Total Time: 40 minutes (0 hours 40 minutes)
Nutrition
FAQ
Can I caramelize a big batch of onions and use them all week?
Yes — and it’s worth doing. Make a full pound or two at once; they shrink dramatically and store well in the fridge for up to 5 days in a sealed container. Reheat only what you need in a small pan with a splash of water.
What’s the right beef fat percentage for smash-style patties?
80/20 ground chuck is the standard call — enough fat to stay juicy when smashed thin against a hot surface. Leaner blends like 90/10 dry out fast once you’ve maximized surface contact, and there’s not enough fat to get good browning.
Do I need to cook the patty all the way through with no pink?
Yes — ground beef must reach 160°F (71°C) internal temperature. Because the meat is ground, any surface bacteria gets mixed throughout, so unlike a whole-muscle steak, you can’t safely serve it pink.