1 Peel shallot and garlic and finely chop. Mix minced meat, shallot, garlic, egg, mustard and breadcrumbs until mixture is smooth. Season with salt and pepper. Divide meat into quarters and shape into patties. Heat butter in a skillet and fry patties on both sides until golden brown, for about 4 minutes. Cooking times may vary, depending on taste and thickness of patties.
2 Cut hamburger buns in half and lightly toast in pan on cut surface. Fry bacon in a dry pan until crispy. Peel onion and cut into rings. Peel avocado, cut in half lengthwise and remove pit. Cut flesh into thin slices. Brush immediately with lime juice.
3 Spread ketchup and some arugula leaves on bun, then place hamburger patty on bun. Spread some ketchup over hamburger patty, then top with a slice of cheese, onion rings, 2 slices of bacon and a few avocado slices. Place bun on top of burger. Serve immediately.