Oklahoma Onion Burger

Let me take you to El Reno, Oklahoma, with nothing but a hot griddle, some beef, and a mountain of onions. If you’ve never had a Sid’s Oklahoma Onion Burger, you’re missing out on one of the best regional burgers in the U.S.—and it’s dead simple to make at home.

The idea is pure genius in its simplicity. A thin patty of seasoned ground beef, smashed onto a hot plate and cooked with a ridiculous amount of thinly sliced onions. The onions caramelise into the burger itself, fusing with the beef fat to form something that’s savoury, sweet, crispy around the edges, and totally addictive.

In this post, I’ll show you how to recreate this roadside diner legend at home, with step-by-step instructions, some historical flavour, and tips for taking it to the next level.

What Is an Oklahoma Onion Burger?

The Oklahoma Onion Burger was born during the Great Depression, when beef was expensive, and onions were cheap. Smart diners like Sid’s Diner in El Reno, Oklahoma which opened in 1989, realized the recipe works and wanted to offer the classic to its customers. You really can stretch a small amount of beef into a whole burger by smashing in a handful of onions.

Today, Sid’s still makes them the old-school way—fresh ground beef, thin-sliced onions, no frills. You’ll get it with a soft white bun, maybe American cheese, and mustard. That’s it. No lettuce, no tomato. No need. It’s all about that crispy beef-onion combo.

Ingredients

The Oklahoma onion burger requires few ingredients. This burger is as simple as they come but when you try it, you will fall in love with the flavor.

• Ground beef
• 1 fresh hamburger bun
• 2 tablespoon butter
• 6.5oz (180g) good quality ground beef
• 1 white onion - sliced paper thin
• 1 tablespoon vegetable oil for frying
• Salt and pepper to taste
• Dill pickle slices
• French's yellow mustard

See recipe card for quantities.

Step by step photos

Check out these photos to see just how easy it is to make the classic Oklahoma onion burger.

1. Step 1: Over a low heat, melt the butter in a pan and toast the burger buns (bottom side). 1-2 minutes until toasted. Set aside

2. Step 2: Place one beef ball into the pan and smash to a thick burger patty.

What Makes It So Good?

It’s the onion-to-beef fusion. The onions don’t just sit on top—they become part of the burger itself. As they caramelise, they sweeten and soften, while the beef crisps around them. It’s crispy, juicy, sweet, salty, and a little smoky from the sear.

When you take that first bite, the combo of melted cheese, beefy flavour, and savoury onions is something special. It’s everything a smash burger should be—fast, messy, and totally unforgettable.

Tips for the Best Onion Burger

Don’t overload with toppings – Let the beef and onions shine. This burger doesn’t need lettuce, tomato, or fancy sauces.with a similar recipe that fits a different diet.

Use the right beef – 70/30 mince gives the best flavor and a good sear. You could use less fatty meat if you want but I recommend the 70/30 meat to fat ratio.

Slice the onions thin – Thicker onions won’t caramelise quickly enough and can overpower the burger.

Smash it hard – This isn’t a thick pub burger. You want max surface area contact for the crust.

Variations

Once you’ve nailed the classic, here are a few fun spins to experiment with:

Double or triple it up – Stack two or three smashed patties for extra indulgence. I did this on my other blog here.

Spicy version – Add sliced jalapeños or hot sauce before serving.

BBQ twist – Mix a bit of BBQ sauce with mustard for a sweet-smoky edge.

Equipment

You’ll need a flat griddle or heavy-bottomed frying pan. Cast iron is ideal. And if you want to do it like the pros, get yourself a metal spatula and a burger press or another spatula for smashing.

Storage

You can do all the preparation for the Oklahoma onion burger a few days ahead of cooking. So if you want to get things ready for your next burger night, go ahead and prepare ahead.

I recommend storing all the ingredients separately in airtight containers.

Final Thoughts

If you love burgers—and let’s face it, who doesn’t?—the Oklahoma Onion Burger needs to be on your list. It’s a masterclass in doing more with less. Just beef, onions, salt, and heat. That’s the magic.

I make these at home when I want something fast, satisfying, and full of flavor. Once you try them, I guarantee you’ll be hooked. You don’t need a grill, just a hot pan and a bit of elbow grease.

So grab some onions, get your smash on, and bring a bit of Oklahoma to your own kitchen.