Light the charcoal in the Big Green Egg and heat to 140°C, with the Cast Iron Grid and the Half Moon Cast Iron Plancha Griddle (with the smooth side facing upward) inside.
Peel the white onions and cut them into rings. Fry the bacon until crisp in about 15 minutes and the onion rings are glossy.
In the meantime, mix the ground beef with the egg, black pepper, paprika powder, Worcestershire sauce, mustard and sea salt. Divide the meat mixture into four equal portions and form these into hamburgers with the Stuff-A-Burger Press (which has been greased with olive oil). Place them in the refrigerator until needed.
Cut the tomato and the gherkins into thin slices. Peel the red onion and cut into thin rings.
Remove the bacon from the Half Moon Cast Iron Plancha Griddle and drain on paper towels. Remove the onion rings and set them aside in a separate dish. Use the EGGmitt to remove the Half Moon Cast Iron Plancha Griddle and bring the temperature of the EGG to 200°C.
Brush the hamburgers with olive oil. Place them on the grid, close the lid of the EGG and grill the burgers for about 4 minutes per side. Meanwhile, cut the hamburger buns in half.
Place the halved buns cut side down next to the burgers and grill for about 30 seconds. Remove the burgers and the buns from the EGG.
Top the bottom halves of the buns with the mixed lettuce, tomato slices, gherkins and onion rings. Add some mayonnaise to taste. Top with a burger, a slice of cheddar, the fried white onion rings and crisp bacon and ketchup or your favourite barbecue sauce. Then cover with the top half of the bun.