Instructions

1. Preheat an oven to 180°C/160°C fan/350°F.
2. Place the walnuts in roasting tray and roast for 8 minutes until they begin to crisp. Remove from the oven and roughly chop.
3. In a large mixing bowl place the beetroot, scallions, feta and chopped walnuts.
4. Gently mash or pulse the black beans with a hand-held blender or food processor.
5. Add the black beans and lemon juice to the other ingredients and gently mix together until well combined.
6. Increase the oven temperature to 200°C/180°C fan/400°F and line two baking trays with parchment.
7. Using damp hands, mould 1 tablespoon of the beetroot mix at a time into burgers of whatever size you like. Repeat with remaining mixture.
8. Add each burger to the baking trays and gently press down with the back of a spoon.
9. Bake in the oven for 30 minutes, gently turning the burgers half way through.
10. Serve in a toasted burger bun or pitta with some relish, salad leaves, crème fraiche and avocado.