Combine the light mayo, ketchup, 1/2 teaspoon English mustard, a pinch of garlic granules, and the gherkin juice in a mixing bowl until smooth.

Cover the burger sauce and refrigerate it while you prepare the potatoes and beef.

Cut the potatoes into 2 cm cubes using a chef's knife on a cutting board.

Toss the potato cubes with paprika, 1 teaspoon garlic granules, dried parsley, salt, and black pepper in a mixing bowl.

Air-fry the seasoned potato cubes at 190°C for 16 to 18 minutes until cooked through and crisp.

Spray a frying pan with oil spray and heat it over medium heat.

Fry the diced onion for about 3 minutes until softened.

Add the lean beef mince to the pan and fry it for 4 to 5 minutes until browned, breaking it up with a spatula.

Crumble the beef stock cube over the browned beef mixture.

Stir the tomato purée, 1 teaspoon English mustard, and boiling water into the beef until the sauce coats the mince.

Fold the crispy air-fried potatoes into the cheeseburger beef mixture until evenly coated.

Scatter the light cheddar and shredded mozzarella over the hot potato mixture.

Cover the pan for 1 to 2 minutes until the cheeses melt.

Divide the loaded potatoes between two serving bowls and drizzle with the chilled burger sauce.

Top each serving with the cooked diced bacon medallions and serve immediately.