Season the chuck flap beef with salt and pepper.
Place the chuck flap beef in a vacuum bag and seal it.
Cook using a sous vide machine at 57°C for 2 hours.
Take out the cooked chuck flap and remove any moisture with a paper towel.
Quickly sear the surface of the chuck flap in a pan with a little oil.
Arrange the beef, rice, salad, and grilled vegetables in a bento box.