If you can, aim for minced beef that's about 30% fat. It'll bind the burger together well.
EASY SWAPS: Support our British cheeses – swap Stichelton into this recipe in place of the blue cheese. Super-creamy and rich (but mellower in flavour than many other blues) Stichelton is wonderful crumbled in a salad and melts beautifully grilled on a slice of sourdough.