Place the ground beef and onion in a large skillet over medium heat.. Cook for 5–7 minutes, or until the beef is cooked through and the onion is soft.
Add the remaining ingredients, and stir to combine. Reduce heat to medium low, and let simmer for 5 minutes.
Spread burger buns with a thin layer of mayonnaise, and broil until toasted. Serve the sloppy joes on the buns with pickle slices.
Notes
Sloppy joe meat will keep for 3–4 days in the refrigerator. You can also freeze sloppy joe meat for up to 3 months in a tightly covered container or freezer bag. Reheat sloppy joe meat in a skillet or in the microwave (use a splatter guard or paper towel on top if using the microwave). You can substitute ground turkey or ground chicken for the ground beef. Variations: add half of a chopped green pepper along with the onion, add ½ teaspoon red pepper flakes for some spice, substitute half the ketchup with bbq sauce.