Using a pestle and mortar, grind all the ingredients for the dersa to a rough paste.

Chop the sardine fillets into small chunks and tip into a large bowl. Add the tomato, if using, herbs, the dersa and 1/4 tsp each sea salt and black pepper, and mix well. The mixture will be quite wet.

Shape the mixture into small fishcakes (about 50g each) and dust generously in the semolina or flour. Heat the oil in a non-stick frying pan over a medium-high heat, then fry the fishcakes on both sides for around 3 mins until golden brown. Serve two or three fishcakes per person with salad, if you like.