Warm 2 tbsp of olive oil in a large casserole over a moderate heat. Add the 6 chicken thighs, skin-side down, and cook until they are pale gold in colour—about 7 to 8 minutes.
Wash the 3 medium leeks thoroughly, shake them dry, and cut them into pieces the length of a wine cork.
Lift the chicken out and add the leeks to the casserole. Cover the pot and let them cook over a low to moderate heat until soft, stirring regularly, for about 12 to 15 minutes.
Pour in a glass of white vermouth (such as Noilly Prat), then grate in the zest and squeeze in the juice of a lemon. Pour in 500ml of chicken stock and return the chicken thighs to the pan, this time skin-side up.
When the liquid comes to a boil, immediately lower the heat so the chicken simmers. Partially cover the casserole with a lid and leave it to cook for about 20 minutes.
Just before serving, pick and chop the leaves from a small bunch of parsley and stir them in, adjusting the seasoning to taste. Serves 3.
The Trick
Make sure that you get some good colour on the skin of your chicken thighs, frying until lightly crisp before you add the other ingredients. Try not to let the leeks brown; instead, keep them soft and pale. They will be sweeter that way.
The Twist
This method is a sound starting point for you to rearrange and adapt according to your taste. Add other ingredients and seasonings at will or as you have on hand, such as green olives, capers, and chopped gherkins. Tarragon leaves are good here, as are chopped thyme leaves. Sometimes I introduce some garlic, added with the leeks, but other times I don’t.