Perfect beef fillet.
This beef fillet is cooked at 56.5 degrees for two hours which leaves the Center of the thick part medium rare and the ends medium for kids.
I served it with a potato and Jerusalem artichoke gratin. Slice the potatoes and artichokes thinly and cook them until almost done in a 50/50 mix of double cream and milk. Salt and pepper to taste. Pour into a pan, grate Parmesan over it and cook on the oven for 20-30 minutes on high heat until browned.