Prep the vegetables: core and thinly slice the cabbage. Dice onion and bell pepper; mince the garlic.
Cook the bacon in a large skillet over medium heat until crisp. Transfer to a plate; keep about 2 tbsp drippings in the pan.
Melt the butter in the drippings. Sauté onion and bell pepper until softened, 3–4 minutes.
Stir in the garlic and cook until fragrant, about 30 seconds.
Add the cabbage. Season with salt, black pepper, smoked paprika, red pepper flakes, and sugar. Toss to coat.
Cook, stirring occasionally, until the cabbage starts to brown on the edges, 6–8 minutes.
Pour in the broth and vinegar. Scrape up browned bits, cover, and steam 2–3 minutes until tender-crisp.
Uncover and cook 2–3 minutes more to evaporate excess liquid and crisp the edges.
Crumble the bacon back in and toss. Adjust seasoning to taste and garnish with parsley.