Cook the bacon in a large skillet over medium heat until crispy and cooked through. Remove the bacon and place it on paper towels to drain. Chop into crumbles.
Place the onion into the skillet with the bacon grease and cook, stirring often, for 5 minutes, or until tender. Side Note: My bacon was very lean so I had very little bacon grease in the skillet so I added a bit of olive oil cooking spray.
Add the cabbages to the skillet and cook, stirring occasionally, for 10-12 minutes, or until softened. Add the bacon crumbles, sugar, and apple cider vinegar then season with sea salt and freshly cracked pepper, to taste; stir to combine and cook for another minute until the liquid evaporates. Taste and re-season if needed. Serve immediately. Enjoy.