Beef & mushroom burgers
Put the onion and mushrooms in a blender or food processor, and whiz until finely chopped. Add the beef, breadcrumbs, herbs and tomato purée, and season with salt and pepper. Blend for a few seconds until the mixture binds together but still has some texture.
Divide the mixture into 8 to 10 pieces, then press into burger shapes using lightly floured hands.
Cook the burgers in a non-stick frying pan or under a hot grill for 12–15 minutes, turning once, until evenly cooked. Serve hot.