Heat a large frying pan over medium-high heat.
Add the minced beef and break it up with a spoon.
Cook, stirring occasionally, for 7–8 minutes or until browned through.
Drain off any excess fat. Season the beef with the salt and pepper, then set aside to cool slightly.
In a medium bowl, whisk together the mayonnaise, ketchup, mustard, sweet gherkin relish, vinegar, sugar, garlic powder, onion powder and paprika until smooth.
Taste the sauce and add more sugar or vinegar if you like.
In a large serving bowl, place the lettuce. Top with the seasoned beef, grated cheddar, chopped onion and sliced gherkins.
Drizzle over the special sauce and toss to coat, or serve it on the side for people to help themselves.
Serve straightaway.