Trout, potato and leek parcels

Preheat the oven to 180˚C, gas mark 4. Put the potatoes in a pan and cover generously with cold water. Bring to the boil; simmer for 8 minutes. Add the leeks and cook for 2 minutes. Drain and steam dry in the colander for 1 minute; season. Meanwhile, put the oil, mustard, shallot, vinegar, capers and tarragon in a small bowl and whisk to make a dressing.

Cut 4 x 30cm squares of parchment or foil. Put 2 on a baking tray; divide the veg between them. Sit the trout fillets on top, then pour over the dressing. Top with the other 2 squares; scrunch the edges together to seal the parcels. Bake for 15-16 minutes, until the fish is cooked through and opaque.