Drain the beans, peel and coarsely grate the onion and deseed and finely chop the chilli. Pick the coriander leaves. Finely grate the lime zest.
Blitz the oats and nuts in a food processor until coarsely chopped. Add 1½ tins of beans, the onion, chilli, ground coriander and cumin, coriander leaves, lime zest and a good drizzle of oil; blitz to combine.
Add remaining beans and pulse just once or twice, so they stay a little chunky. Transfer to a bowl.
Divide into 6 balls then flatten into burgers on a clean surface dusted with flour and smoked paprika. Place on a tray and chill for at least an hour.
If using bread rolls, split in half. Place the bread, cut-side down, on the grill and cook until lightly charred. Set aside.
Cook the burgers for 4 to 5 minutes each side, or until lightly charred and cooked through.
Scatter rocket on 6 roll halves or slices of bread, top with burgers. Top with fresh tomato salsa, slices of avocado, rocket and the remaining bread slices. Serve with lime cheeks for squeezing over.