1. Preheat oven to 425°F.
2. Toss potatoes with 4 tbsp olive oil, salt, and pepper. Spread on baking dish.
3. Bake potatoes for 40 minutes, turning halfway, until golden.
4. Heat remaining olive oil in a pan over medium-high heat. Add onion, cook until softened.
5. Add beef, cook until browned. Stir in paprika, onion powder, garlic powder. Set aside.
6. Combine mayonnaise, chopped gherkins, mustard, ketchup, paprika, onion powder, and garlic powder. Add water to desired consistency.
7. Divide lettuce among bowls. Top with potatoes, beef, cheese, tomatoes, red onion, and sliced gherkins.
8. Drizzle with sauce and serve.