- MIX together the ground beef, salt, black pepper, Worcestershire sauce, Dijon mustard, grated onion, and egg until well combined.
- FORM the beef into 4 even patties and chill in the fridge for 1 hour.
- SELECT Preheat on the Cosori Air Fryer and press Start/Pause.
- RUB the patties with olive oil and place the burgers into the preheated air.
- SELECT Steak, adjust the time to 8 minutes, and press Start/Pause.
- FLIP the burgers halfway through cooking to ensure even browning.
- ADD the slices of cheddar cheese to each of the burgers with 1 minute of cooking left.
- SERVE on mini slider buns.