Cook the potatoes in boiling water until tender, about 15-20 mins. Meanwhile, coarsely mash the sardines in a bowl. Mix in 3 tbsp chopped parsley and half the lemon zest and juice. Meanwhile, mix the mayonnaise and yogurt with the remaining parsley, lemon zest and juice and some seasoning & garlic if preferred.
Drain the potatoes, then mash until smooth. Gently mix into the sardine mixture and season. Shape into 8 fat fish cakes using floured hands, then dust lightly with the seasoned flour.
Heat half the oil in a non-stick frying pan and fry half the fish cakes for 3-4 mins on each side until golden and crisp. Keep warm; repeat with remaining oil and fish cakes. Serve with the lemony mayonnaise and lemon wedges.
PER SERVING: 287 calories, protein 16g, carbohydrate 29g, fat 13 g, fibre 2g, sugar 2g, salt 0.67 g