Make the special sauce. In a small bowl, whisk together mayonnaise, sugar-free ketchup, mustard, pickle relish, garlic powder, onion powder, vinegar, and paprika. Season with salt and pepper.
Chill while you prep the rest to let the flavors meld.
Prep the veggies. Chop the romaine, slice tomatoes and red onion, and dice the pickles. If using avocado, dice it just before serving and toss lightly with a little lemon juice to prevent browning.
Season the beef. In a mixing bowl or right in the skillet, combine ground beef with salt, pepper, onion powder, garlic powder, and smoked paprika. Mix gently—don’t overwork the meat.
Cook the beef. Heat a large skillet over medium-high.
Add oil if using lean beef. Cook the seasoned beef, breaking it into crumbles, until browned and cooked through, about 6–8 minutes. Drain excess fat if needed, but leave a little for flavor.
Melt the cheese. Turn off the heat and scatter shredded cheese over the hot beef, letting it melt.
If using sliced cheese, lay slices on top, cover the pan for a minute to soften.
Assemble the bowls. Divide lettuce among bowls. Top with cheesy beef, tomatoes, onions, pickles, and avocado. Sprinkle with parsley if you like.
Finish with sauce. Drizzle the special sauce over each bowl.
Add extra pickles or a light dusting of black pepper if you’re feeling bold.