Step 1

Place potato in a large saucepan of water. Bring to the boil over high heat. Boil for 8 to 10 minutes or until tender. Drain well. Return to pan over low heat. Add butter. Mash until smooth. Remove from heat. Season with salt and pepper. Transfer to a heatproof bowl. Set aside to cool.

Step 2

Meanwhile, place fish in a deep frying pan. Cover with cold water. Season with salt and pepper. Cover pan. Place over medium heat. Bring to a simmer. Remove from heat. Stand for 1 minute.

Step 3

Carefully transfer fish to a board. Remove and discard skin. Flake fish into pieces.

Step 4

Add onion, tarragon, parsley, egg and flour to potato mixture. Stir to combine. Add fish. Fold to combine. Using 1/4 cup mixture at a time, shape into 16 patties. Coat in breadcrumbs. Refrigerate for 15 minutes.

Step 5

Pour enough oil into a frying pan to come 1 to 2cm up side of pan. Heat over medium-high heat. Cook fish cakes, in batches, for 3 to 4 minutes each side or until golden all over and heated through. Drain on a paper towel-lined plate. Serve fish cakes with tartare sauce, baby rocket and lemon wedges.