Drain the tuna and put in a medium bowl. Mash the flesh with a fork. Add the egg, onion, herbs, chilli flakes, mustard, salt and pepper. Mix well.
2
Roll the mixture into one big ball, then cover and chill in the freezer for 30 minutes. When you’re ready to cook the fishcakes, take the mixture out of the freezer and divide into four. Shape each portion into a fishcake and sprinkle both sides with flour.
3
Heat the oil in a medium frying pan over medium heat, then cook the fishcakes for 7–10 minutes on each side, until golden brown.
4
Serve immediately, with chives scattered over and lime slices on the side.