Copycat In-N-Out Flying Dutchman Burgers (Keto Low Carb)

1. Sauté your onions in butter until softened and set aside.
2. Season your ground beef with salt & pepper.
3. Shape the seasoned beef into patties and fry on medium-high heat for 2 minutes.
4. Spread your mustard on each patty and flip.
5. Top the cooked patties with American cheese, add a bit of water to the pan, and cover for 1 minute to melt the cheese.
6. Remove lid, serve the cheesy patties with the sautéed onions, pickles, yellow chilis, and your choice of condiments (including the homemade sauce).

To make the sauce:

1. Combine 1/2 cup mayo, 3 tbsp sugar-free ketchup, 2 tbsp dill relish, 1.5 tsp white vinegar, and 2.5 tbsp sweetener in a bowl. Mix thoroughly until well combined.