Wash the sweet potato, cut it into thick slices and pat dry. Prepare the tomato, red onion and lettuce.
Brush the sweet potato slices with olive oil, salt them and cook in a frying pan or in the oven until soft and lightly browned at the edges.
Season the beef mince with salt, pepper and a little mustard, shape it into a patty and fry it in the hot pan on both sides until cooked right through.
Set the tomato and red onion aside briefly, or put them in the pan for a moment if you like, so they become a little milder. Only use the lettuce at the end so it stays crisp.
Use two sweet potato slices each as the bottom and top, and layer the beef mince patty, tomato, red onion, lettuce and a little mustard in between.
Serve the burger straight away, while the sweet potato is warm and the patty juicy.
Good to know
A hearty burger that still doesn't feel heavy. The sweet potato replaces the classic bun in a simple, honest way.
Swaps
Beef mince → chicken mince (similar protein content); mustard → yoghurt and mustard cream made from natural yoghurt and mustard (milder, adds protein; contains milk); butterhead lettuce → rocket (stronger flavour, a little more bitter); olive oil → ghee (heat-stable and aromatic; contains milk).
Allergens
The recipe is naturally gluten-free if you choose a mustard without additives; it contains mustard, one of the allergens that must be labelled. Raw onion can be a little sharp for children, and in pregnancy the beef mince should be cooked right through.
