Season the chicken with salt, pepper and lemon juice. Set aside. Set the oven to Gas Mark 4, 180°C, 350°F. Toast the walnuts in a dry pan, then tip them into the processor with the other dressing ingredients. Whiz for a few seconds. Taste for seasoning, leave in the fridge until ready to serve. Heat a pan or black grill pan. Cook the chicken skin side down for 4-5 minutes to get a delicious crisp skin. Turn over and cook for another 2-3 minutes. Finish the cooking for another 10-15 minutes in the hot oven. Very good served with spinach, a few new potatoes and a spoonful of the dressing on top. Any leftover dressing will last for a week in the refrigerator.