Gently shape the 8 oz ground beef into a 3/4-inch-thick patty slightly wider than the desired finished size (it will shrink while cooking). Press a shallow dimple into the center with your thumb to promote even cooking. Season both sides with 1/2 tsp kosher salt and 1/4 tsp black pepper just before cooking.

Cook Patty

Preheat a grill or a heavy skillet (cast iron) over medium-high heat. Brush the grill grates or pan with 1 tbs vegetable oil to prevent sticking. Place the patty on the hot surface and cook undisturbed for 3-4 minutes to develop a crust. Flip and cook 3-4 minutes more for medium doneness (internal temperature about 140-145°F / 60-63°C). For well done, cook 1-2 minutes longer. Remove the patty and let rest on a plate for 3-4 minutes while you finish onions and assemble.

Grilled Maui Onions

Sauté Onions

While the patty cooks (or in a separate pan), heat a skillet over medium heat. Add 1 tbs unsalted butter and 1/2 tbs olive oil. When the butter is foaming, add 1/2 cup sliced Maui onion rings in a single layer. Season with 1/8 tsp salt and a pinch (1/16 tsp) black pepper. Cook, stirring occasionally, until the onions are golden and caramelized at the edges, about 6-8 minutes. If they begin to stick, lower the heat slightly and stir more frequently. Remove from heat and keep warm.

Hula Sauce

Make Sauce

In a small bowl, combine 1/4 cup mayonnaise, 2 tbs ketchup, 1 tsp strained pineapple juice, 1/2 tsp soy sauce, 1/4 tsp finely grated fresh ginger, 1/2 tsp rice vinegar, and 1/8 tsp hot sauce (optional). Whisk until smooth and taste; adjust seasoning with 1/16 tsp salt or more pineapple juice if you prefer a sweeter tang. Chill briefly if time allows to meld flavors.

Assemble & Serve

Because the menu notes 'ask for no bun', serve the burger open or wrapped in lettuce. Place 1-2 large lettuce leaves on a plate as the base (if using). Spread about 1.5 tbs of Hula Sauce on the lettuce or directly onto the patty. Set the rested 8 oz burger patty on top, spoon the warm grilled Maui onions (about 1/2 cup) over the patty, and add optional tomato slices and pickles if desired. Serve immediately, providing extra sauce on the side. If a bun is requested later, this recipe pairs with a toasted brioche bun.