shredded iceberg lettuce
1 large potato (about 285g/10oz), peeled and cut into large chunks
1 small red onion, finely chopped
3–4 ripe tomatoes, sliced
½ tsp dried chilli flakes
sauces of your choice, such as mayonnaise, mustard or ketchup (optional)
400g tin red kidney beans, drained and rinsed
1 slice bread (about 65g/2¼oz), blitzed to crumbs (see recipe tip)
1 tsp ground cumin
1 tsp salt
3–4 tbsp vegetable oil
4 burger buns, cut in half