You can use a pastry cutter to help with the shape if you like. Let the burgers rest in the fridge for at least 20 minutes.
Cook the burgers (5 – 6 minutes on each side) in a hot frying pan with a splash of oil.
Serve the burger on a bun with a spoonful of the beetroot relish, slices of tomato and salad leaves. Garnish with homemade onion rings and chips of your choice.
...for the beetroot and red onion relish
Heat a medium saucepan with the butter and sweat the onions, garlic, chilli flakes and beetroot on a low heat, with seasoning, until it starts to caramelise. This should take about 10-15 minutes.