Caramelize the Onions: Heat a pan over medium heat (level 6/9) with a little oil. Add the sliced onions and a pinch of salt. Cook slowly, stirring often. Add 1 tsp sugar to help them caramelize faster. If they start sticking, add small splashes of water and continue cooking until soft, golden, and jammy.
Prepare the Sauce: In a bowl, mix mayonnaise, water, buffalo hot sauce, salt, pepper, paprika, and garlic powder until smooth. Set aside.
Cooking the Smash Patties: The beef is first shaped into round (80g each) patties and gently pressed flat. Season with salt, pepper, and garlic powder. Place the patties seasoned side down into a hot pan. Peel off the baking paper once the patty hits the pan. While the baking paper is still on top, you can smash the patty once more to get it extra thin and crispy. Season the second side, then flip and cook until deeply browned. Add one slice of melting cheese to each patty and let it melt completely.
Assembling the Burger: Toast the Texas toast slices separately in butter until golden and crispy. This prevents them from soaking up too much fat and keeps the texture perfect. Once everything is ready, assemble the burger at the end: toasted Texas toast → sauce → patties → caramelized onions → top toast.