Cook bacon in a 12-inch cast iron skillet until browned. Use a slotted spoon to remove and set aside. Reserve 2 tablespoons pan drippings.
In the same pan that you cooked the bacon, sauté the onions, just until they start to soften, about 3 minutes. Add the cabbage and apple cider vinegar. Cover and cook for 3 - 5 minutes or until cabbage has wilted.
Add in kielbasa, caraway, crushed red pepper. Season to taste with salt and pepper.
Sprinkle half of the cheddar cheese on top of the kielbasa and cabbage mixture. Top with tater tots. Bake in preheated oven for 15 minutes.
Remove from oven, top with remaining cheese and reserved bacon. Bake for an additional 5 - 10 minutes or until tater tots are browned and cheese is melted. Serve.