Prep the produce: Core the cabbage and slice it into thin shreds.
Slice the onion and mince the garlic. Chop the bacon into bite-size pieces.
Crisp the bacon: Place the bacon in a large, cold skillet. Turn the heat to medium and cook, stirring occasionally, until the bacon is crisp and the fat has rendered, about 8–10 minutes.
Use a slotted spoon to transfer bacon to a plate, leaving the fat in the pan.
Sauté the aromatics: Add the onion to the bacon fat and cook until softened and lightly golden, 3–4 minutes. Stir in the garlic and cook 30 seconds, just until fragrant.
Add the cabbage: Pile the sliced cabbage into the skillet. It may look like a lot, but it will wilt.
Toss to coat the cabbage in the bacon fat and aromatics.
Season well: Sprinkle in smoked paprika, crushed red pepper flakes (if using), a good pinch of salt, and black pepper. If the pan seems dry, add the butter for extra gloss and flavor.
Cook until tender: Continue cooking over medium to medium-high heat, stirring every couple of minutes, until the cabbage is tender with a slight bite and has some caramelized edges, about 8–12 minutes. Don’t rush it—those browned bits add flavor.
Finish and taste: Return the bacon to the skillet.
Drizzle in apple cider vinegar or lemon juice to brighten. Toss well and taste; adjust salt, pepper, and heat as needed.
Serve: Garnish with chopped parsley or chives. Serve hot as a side, or top with a fried egg or grilled sausage for a full meal.