Fill the kettle and boil it. Rinse the rice under cold water. Tip it into a small pan. Pour in 300ml hot water from the kettle. Cover. Bring to the boil. Turn the heat right down. Gently simmer for 25 mins till the water has been absorbed.
Take the rice off the heat. Leave it to steam with the lid on for 5 mins to finish cooking the rice.
While the rice is cooking, slice the leaves off the radishes. Finely slice the leaves. Quarter the radishes. Finely grate the zest from the lemon. Juice it. Finely chop the chervil, throwing away any thick stalks.
Whisk the lemon juice with 1 tbsp olive oil and some salt and pepper to make a lemony dressing. Add the radishes, radish leaves, chervil and the rocket. Toss to mix. Put to one side.
Heat your grill to high. Line your grill pan with foil. Drizzle ½ tbsp olive oil over each fish. Season with salt and pepper. Gently rub the oil in to both sides of the fillets.
Pop the whiting fillets on a rack in the grill pan, skin side down. Grill for 3-5 mins till the fillets are a dark white colour and look cooked through. Carefully turn the fillets over so they're skin side up. Grill for 3-4 mins till the skin is crisp.
Fluff the rice up with a fork. Mix it with the rocket and radishes. Stir to mix everything well and coat the rice in the lemony dressing. Serve with the crisp whiting fillets.