Place the bacon slices in a cold skillet and turn the heat to medium, cooking until the fat has rendered and the bacon is crispy.
Remove the bacon and set it aside on a paper towel to drain, keeping about a teaspoon of the bacon fat in the pan for flavor.
In a small bowl, season the ground beef with sea salt, black pepper, and garlic powder, then gently form into two equal, thin patties.
Increase the skillet heat to medium-high and sear the beef patties for about 3 to 4 minutes per side until a golden crust forms.
During the last minute of cooking, place the cheddar cheese slices onto the patties and cover the pan with a lid to melt the cheese completely.
Wash and pat dry the large romaine lettuce leaves to use as your sturdy burger base.
Thinly slice the red onion and tomato to prepare your fresh toppings.
Assemble the burger by stacking the two cheesy patties onto the lettuce leaves, followed by the crispy bacon, tomato, and onion.
Drizzle with yellow mustard and fold the lettuce leaves over the top to serve as a clean, handheld wrap.