Heat vegetable oil in a large cast iron skillet over medium high heat. Add ground beef and cook until browned, about 3-5 minutes, making sure to crumble the beef as it cooks; drain excess fat.
Add onion and bell pepper. Cook, stirring occasionally, until tender, about 3-4 minutes.
Stir in tomato paste, garlic, paprika, chili powder and cayenne pepper until fragrant, about 1 minute.
Stir in beef stock, scraping any browned bits from the bottom of the skillet.
Stir in ketchup, Dijon, Worcestershire and brown sugar; season with salt and pepper, to taste. Bring to boil; reduce heat and simmer, stirring occasionally, until thickened and flavors have blended, about 15-20 minutes.
Serve immediately.
*TO FREEZE: Let cool completely; portion into plastic freezer bags in individual servings, squeezing out any excess air before sealing. Lay the bags flat in a single layer in the freezer (this will help them freeze quickly). To reheat, thaw overnight in the fridge, reheating over low heat, stirring occasionally, until heated through.
