Fry the bacon strips until crisp in a skillet over low-medium heat. Set aside.

In a bowl, mix the meat, red onions, lemon juice and Dijon mustard. Form a large patty.

In another pan, cook the meatball until the meat is well cooked. Make sure to turn it halfway through cooking.

Prepare your mayonnaise at the same time. In a small bowl, whisk together the mayonnaise, lemon juice and spices to taste. Set aside.

Place the patty on a plate. Garnish with spinach and cherry tomatoes.

Place the bacon on top and spread the mayonnaise.