There’s a reason why so many people swear by ordering their In-N-Out burgers “Animal Style.” One of the key components that makes this upgrade so irresistible is the grilled onions — tender, caramelized, golden-brown, and loaded with sweet and savory flavor.
These onions aren’t just sautéed; they’re cooked low and slow until they practically melt into the burger, infusing every bite with depth and richness.
Whether you’re building your own smash burgers at home, topping off fries, or just want to recreate that signature flavor without waiting in a drive-thru, this In-N-Out grilled onions recipe is a must-know. It uses simple ingredients, takes minimal effort, and delivers big on the classic flavor you love.

Why You’ll Love This Recipe
This recipe brings restaurant-level results into your home kitchen with just a handful of pantry staples.
The onions cook down slowly to develop a jammy, slightly tangy, rich flavor that pairs well with everything from burgers and sandwiches to eggs and grain bowls. Plus, you can make them ahead, freeze them, or keep them in the fridge to upgrade any meal in seconds.
What You’ll Need
Ingredients:
- 2 large yellow onions, finely chopped
- 2 tablespoons vegetable oil or neutral oil
- 2 tablespoons unsalted butter
- ½ teaspoon salt (or to taste)
- 1 teaspoon white vinegar (for tanginess, optional but authentic)
- 1 to 2 teaspoons water (as needed to deglaze and prevent burning)
Pro Tips
- Chop finely for authenticity – In-N-Out onions are minced more than sliced. A fine chop helps them caramelize evenly and match the restaurant texture.
- Low and slow is key – Don’t rush it. Cooking over medium-low heat for 20–30 minutes brings out the natural sweetness.
- Deglaze as needed – Add small splashes of water during cooking to loosen flavorful browned bits from the pan.
- Add vinegar for a tangy kick – Just a dash at the end mimics the mild acidity In-N-Out onions are known for.
- Cook in batches for more – This recipe can easily be doubled or tripled. Leftovers freeze well and reheat beautifully.
Tools Required
- Large nonstick or cast iron skillet
- Sharp chef’s knife
- Cutting board
- Wooden spoon or heat-safe spatula
- Measuring spoons
- Small ramekins or containers for serving
Substitutions and Variations
- No butter? Use all oil.
- Add garlic: For extra depth, stir in minced garlic during the last 5 minutes.
- Use red onions: For a slightly different flavor and a deeper color, red onions work well too.
- Sweet version: Add a pinch of sugar early in the cooking to intensify sweetness.
- Spicy twist: A small pinch of cayenne or smoked paprika adds gentle heat.

Make-Ahead Tips
These onions store well in the fridge for up to 5 days in an airtight container. You can also freeze them in small portions for up to 2 months.
Reheat in a skillet or microwave until warm. They’re perfect for batch prep when making burgers or grilled sandwiches at home.
Instructions
1. Finely chop the onions
Peel and finely chop the onions into small pieces. Avoid slicing; the authentic In-N-Out style uses finely chopped onions that caramelize evenly.
2. Heat the skillet
In a large skillet, heat oil and butter over medium-low heat until melted and shimmering.
3. Add onions and salt
Add the chopped onions and salt to the pan. Stir to coat in the oil and butter. Cook over medium-low heat, stirring every few minutes to prevent burning.
4. Caramelize slowly
Continue cooking the onions for 20–30 minutes, stirring frequently. Add a teaspoon or two of water every so often to deglaze the pan and prevent sticking.
5. Finish with vinegar
When the onions are deep golden and soft, stir in the vinegar. Cook for 1–2 more minutes, then remove from heat.
6. Serve
Spoon the onions onto burgers, sandwiches, fries, or store for later use.
Leftovers and Storage
Let onions cool completely before storing. Keep in an airtight container in the refrigerator for up to 5 days. Reheat gently in a pan or microwave in 30-second intervals. You can also freeze them in small portions for quick use later — thaw overnight or heat directly from frozen in a skillet.
Recipe FAQ
1. Are these the same onions used in Animal Style fries?
Yes, these are the same slow-cooked, caramelized onions used in Animal Style burgers and fries. The fine chop and extended cooking time are key.
2. Can I speed this recipe up?
You can sauté onions over higher heat for a quicker version, but the depth of flavor from slow caramelizing is what makes it true to In-N-Out’s version.
3. What kind of onion works best?
Yellow onions are traditional and offer the perfect balance of sweetness and bite. White onions will work in a pinch, but avoid red for this recipe.
4. Can I make a large batch?
Absolutely. This recipe scales easily. Just be sure not to overcrowd the pan, or the onions will steam rather than caramelize.
Bring the Drive-Thru Flavor Home
In-N-Out’s grilled onions are the unsung hero of their iconic burgers and fries. With this easy stovetop method, you can bring that signature flavor to your own kitchen anytime. Use it to level up your homemade burgers, add richness to grilled cheese, or spoon over hash browns and rice bowls.
Give it a try and let me know how it turned out. Leave a comment below if you made any changes or have questions about technique. I’m happy to help you master your next burger night.