Fire-Roasted Tomato Sauce (Slow Cooker)
- Heat oil in a 12-inch skillet over med-high heat until shimmering.
- Add onions, garlic, tomato paste, oregano, and red pepper flakes and cook until onions are softened and lightly browned, 8-10 minutes.
- Stir in diced tomatoes and cook until dry and lightly browned, 8-10 minutes.
- Stir in wine, scraping up any browned bits, and simmer until thickened, about 5 minutes; transfer to slow cooker.
- Stir crushed tomatoes, tomato sauce, and liquid smoke into slow cooker.
- Cover and cook until sauce is deeply flavored, 9-11 hours on LOW or 5-7 hours on HIGH.
- Before serving, stir in parsley and season with salt and pepper to taste.
- Serve over hot cooked pasta.