01 - Whisk together mayonnaise, ketchup, yellow mustard, sweet pickle relish, white vinegar, smoked paprika, and black pepper in a small bowl until smooth. Set aside to allow flavors to meld.
02 - Place a large skillet or griddle over medium-high heat and allow it to get thoroughly hot.
03 - Divide ground beef into 8 equal portions and roll into balls. Season generously with kosher salt and freshly ground black pepper.
04 - Place beef balls on the hot skillet. Using a heavy spatula, press each ball firmly to create thin, crispy patties. Cook undisturbed for 2-3 minutes until deeply browned and crispy. Flip and cook 1-2 minutes longer. Remove and set aside.
05 - Distribute mixed salad greens evenly among four serving bowls. Arrange cherry tomatoes, red onion, dill pickles, avocado slices, and shredded cheddar cheese on top of the greens.
06 - Place the crispy smashed beef patties over each vegetable bowl.
07 - Drizzle generously with prepared smash sauce and sprinkle with crispy fried onions. Serve immediately while patties are still warm.