Shoyu Smash Burgers with Smoked Brown Butter Mayo
You know around here, the griddle stays hot, the vibes are always backyard-ready, and bold flavor is non-negotiable! There is nothing quite like a classic smash burger—those paper-thin, ultra-crispy lacy edges, and that perfect, gooey cheese melt. But today, we are taking this crowd-pleaser and giving it a massive flavor upgrade
We’re pairing traditional American comfort food with centuries-old Japanese craftsmanship by introducing Kioke Reserve Soy Sauce to the steel.
If you think all soy sauce is just “salty,” this recipe is going to completely change your perspective. Kioke Reserve is a premium, artisanal shoyu traditionally brewed in Japan inside authentic cedar barrels (Kioke). That aging process gives it a remarkably smooth, rich, and deeply complex umami profile. When it hits that hot beef on a screaming hot griddle, it creates an absolutely mind-blowing, caramelized flavor crust.
Layered with sweet, caramelized onions and a rich, smoked brown butter mayo, this is hands-down the best burger I have made all year. Let’s go!
Shoyu Smash Burgers with Smoked Brown Butter Mayo
Ingredients
The Burgers
- 1.5 lbs 80/20 ground beef rolled into 8 loose 3-oz balls (keep cold)
- 4 brioche buns sliced
- 8 slices sharp American or Gouda cheese
- 2 tbsp Kioke Reserve Soy Sauce (or high-quality standard shoyu/tamari)
- 1 tsp coarse kosher salt
- 1 tsp coarse black pepper
Shoyu Caramelized Onions
- 2 large yellow onions thinly sliced
- 2 tbsp unsalted butter
- 1.5 tbsp Tamari or standard Shoyu
- 1 tsp brown sugar
Smoked Brown Butter Mayo
- 4 tbsp unsalted butter
- 1/2 cup mayonnaise
- 1 tsp garlic powder
- 1 tsp Kioke Reserve Soy Sauce (or standard shoyu)
Instructions
- Make the Caramelized Onions: Melt 2 tbsp butter on griddle or skillet over medium heat. Add sliced onions and cook slowly, stirring occasionally, until soft and deeply golden brown (about 15-20 minutes). Stir in 1.5 tbsp tamari (or standard shoyu) and brown sugar. Let glaze for 2 more minutes, then move to cooler part of grill or remove from skillet.
- Make the Brown Butter Mayo: Melt 4 tbsp unsalted butter in a small saucepan over medium heat. Swirl frequently until the foam subsides, the butter turns a rich golden-amber color, and smells intensely nutty with small dark specks at the bottom. Pour into a bowl and let cool slightly. Whisk the cooled brown butter together with the mayonnaise, garlic powder, and 1 tsp Kioke Reserve soy sauce until smooth and glossy.
- Preheat your outdoor griddle or heavy cast-iron surface to high heat.
- Spread a thin layer of plain butter or a touch of your brown butter mayo onto the cut sides of the brioche buns. Toast on the hot griddle until beautifully golden brown, then set aside.
- Place the cold beef balls onto the dry, hot griddle surface. Using a heavy burger press or a sturdy spatula (with a piece of parchment paper in between to prevent sticking), smash the beef completely flat. Hold down firmly for 2-3 seconds for maximum contact. Season immediately with a pinch of salt and coarse black pepper.
- Let the patties sear undisturbed for 90 seconds until the edges are dark, crispy, and lacy. Just before flipping, drizzle roughly 1/2 tsp of Kioke Reserve soy sauce directly onto the lacy edges of each patty. Flip immediately.
- Immediately place a slice of cheese on each flipped patty. Stack two patties together as the cheese melts.
- Build the Burger: Slather a generous spoonful of the Smoked Brown Butter Mayo onto the bottom bun. Place your double patty stack on top, crown generously with the warm Shoyu Caramelized Onions, close the bun, and serve immediately.
💡 Backyard Chef Tips for This Recipe
🪵 Preserving the Premium Flavor: While standard shoyu or tamari is great for cooking down in the caramelized onions, save your premium Kioke Reserve for the actual burger baste and the final mayo. Because it’s unboiled on the burger crust, the delicate cedar-barrel aroma and live flavor notes hit your palate instantly. Of course, you can always use whatever soy sauce you’ve got on hand.
🥶 Keep the Beef Cold: Keep your rolled beef balls in the fridge right up until they hit the griddle. Cold fat hitting a screaming hot griddle surface is the secret to getting those perfect, crispy, lacy smash burger edges!
Did you make this recipe? Tag me in your photos at @WhipItUpWithWilliams!
🔄 Don’t have Kioke Reserve yet? No worries! You can still make an incredible version of this burger using what’s in your fridge right now. Sub in your favorite high-quality regular Shoyu or Tamari for the griddle baste and the mayo. It won’t have those deep, woody cedar-barrel notes that make Kioke Reserve so unique, but it will still give you a fantastic, savory umami crust that beats a standard burger any day of the week!
