In a small mixing bowl, whisk together the mayonnaise, sugar-free ketchup, yellow mustard, dill pickle relish, white vinegar, smoked paprika, and onion powder until smooth. Set aside in the refrigerator to allow flavors to meld.
Place a large skillet over medium-high heat. Add the ground beef and cook until browned, approximately 7–8 minutes, breaking it into small crumbles with a spatula.
Season the beef with garlic powder, sea salt, black pepper, and Worcestershire sauce. Stir well to incorporate. Once fully cooked, drain any excess rendered fat and remove from heat.
Divide the shredded romaine lettuce evenly between four serving bowls.
Top the lettuce with the warm seasoned ground beef, followed by the shredded cheddar cheese, sliced red onions, and dill pickle slices.
Drizzle the prepared special sauce generously over each bowl.
Garnish with toasted sesame seeds and serve immediately.