To make the lemon mayonnaise, mix together the mayonnaise, yoghurt, lemon rind and juice, parsley and capers in a large bowl. Cover and chill

Cut the fish fillets into thin strips.

Place the beaten egg and one shallow bowl, in another bowl mix together the breadcrumbs, sesame seeds,

Dip the fish strips, one at a time into the beaten egg, then into the breadcrumb mixture and toss until evenly coated. Put on a small clean plate

Heat about 2.5 cm of oil in a frying pan.

Deep fry the strips in batches for 2 to 3 minutes until lightly golden

Remove with a slotted spoon, drain on kitchen paper and keep warm in the oven while frying the remainder

Garnish with watercress and serve hot with lemon wedges and the chilled lemon mayonnaise