Sear the beef in the instant pot with 1 tbsp of vegetable oil until nicely browned. You will need to work in batches to avoid cooling down the pan too quickly.
Sear the onions and carrots and brown nicely.
Add the rest of the ingredients from the "beef braise" section with the browned meat to the instant pot. Close the lid and set on high pressure for 35 minutes.
Once the timer goes off, let it cool for 20 minutes. Manually release the rest of the pressure.
Strain the liquid from the braise and save 250ml of the braising liquid. Once the beef is cool enough to handle, shred it into small pieces with your hands.
Begin by melting the butter in the pan. Add the flour and whisk.
Cook over low heat until a blond colour roux is made. About 5 minutes.
Add the braising liquid slowly and whisk continually to make a smooth sauce with no lumps of flour.
Once all the liquid is mixed in add the shredded beef, allspice, marmite and fresh black pepper. Cook gently until the mixture thickens slightly for about 2 minutes. Taste. Make sure it's seasoned nicely with salt and pepper.
Let this cool completely on a tray for approximately two hours or overnight in the fridge.
Once the mixture is completely cooled, begin to roll it into little balls smaller than a ping pong ball.
Get three containers with high sides and fill one with flour, one with beaten eggs and the other with the panko bread crumbs. Dredge the balls in the flour, then the eggs and finally the panko breadcrumbs.
Once breaded you can store some in the freezer for later or fry some now in a deep fryer at 170C/350F for about 5-6 minutes or until nicely golden and hot in the middle.
Serve with a side of mustard and a good cold beer.