For best results, sear the beef before adding it to the slow cooker - this develops deeper flavors.
The beef can be stored in the refrigerator for 3-4 days or frozen for up to 3 months.
To reheat, warm in a covered skillet with 2-3 tablespoons of beef broth to maintain moisture.
For a lower-carb option, serve the beef in lettuce cups or over cauliflower rice instead of on buns.
The flavors actually improve after 24 hours as the spices continue to meld.