Preparation

• 1
  Preheat the oven to 200 degrees, 180 degrees fan oven.
• 2
  Put 1-2 tablespoons of olive oil in a roasting tin or dish, big enough to hold the two plaice comfortably, then warm in the oven for a few minutes.
• 3
  Meanwhile, slice the potatoes, skin on, fairly thinly but not so thin that they crisp too much in the oven. Peel the red onion and chop it into fairly thick slices. Tip both into the roasting tin, toss them in the warmed olive oil to coat them, season with salt and pepper then roast for 15 minutes.
• 4
  Clear a small space in two corners of the tin and add the tomatoes, drizzle a little olive oil over them and return to the oven for another 5 minutes.
• 5
  Lay the two plaice fillets on top of the potato and onion, season with salt and pepper and dot with a little butter. Bake for another 8-10 minutes, or until the fish is opaque and flakes easily.
• 6
  Meanwhile, peel the garlic and slice it thinly, then wash and chop the leek into 5 or 6 lengths and slice them thinly. Heat a tablespoon of olive oil in a small saucepan over a low light and very gently sauté the sliced leek and garlic with a squeeze of lemon for 5-7 minutes, until the leeks are soft and just beginning to brown.
• 7
  Carefully place the fish, on bed of roasted potato and onion, onto two warmed plates along with the tomatoes. Use tongs to lift out the leek and garlic and arrange it on top of the fish.
• 8
  Quickly add the juice of half a lemon and a knob of butter to the leek pan, stir a small handful of chopped parsley into the melted butter then spoon it on top of the two fish.
• 9
  Serve immediately with green vegetables, such as broccoli, green beans or asparagus, garnished with a wedge of lemon.