Optional for serving: Sliced cheddar cheese, pickles
Instructions
Heat the oil in a large skillet over medium-high heat. Add the ground beef and cook, undisturbed, until browned on one side, about 4 minutes. Break the beef into small crumbles and continue to cook until no longer pink, about 3 more minutes. Sprinkle with ¼ teaspoon salt. Transfer to a 4-to 6-quart slow cooker.
To the now-empty skillet, add the carrots, onion, bell pepper, and ¼ teaspoon salt. Cook, stirring periodically, until softened, about 5 minutes. Stir in the garlic and chili powder until fragrant, about 1 minute. Transfer to the slow cooker.
Add the tomato paste, mustard, ketchup, Worcestershire sauce, brown sugar, vinegar, broth, and remaining ½ teaspoon salt to the slow cooker and stir to combine. Cover and cook on low heat for 4 hours or high heat for 2 hours, until the vegetables have softened.
Serve on Kaiser rolls with toppings of choice.
Notes
For the vinegar, apple cider vinegar or lemon juice also work.
TO STORE: Transfer the leftover filling to an airtight container and refrigerate for up to 4 days.
TO REHEAT: Warm in a skillet set over medium-low heat or in the microwave.
TO FREEZE: Freeze flat in a freezer bag with the air pressed out or in an airtight container. The filling will keep up to 3 months in the freezer; thaw in the refrigerator before reheating.