Recipe for fish fumet

For 0.5 litre of fumet: 750 g of fish trimmings (bones, heads etc) - 2 large onions - 2 shallots - 2 large carrots - one bouquet garni (thyme, laurel, parsley) - half a lemon - 1 large glass of white wine - 1 litre of water - coarse salt - pepper

Peel 2 large onions, 2 shallots and 2 large carrots and chop them up finely.
Smash up the fish bones, place them in a big pan with the chopped vegetables, add the bouquet garni and half a lemon. Pour in a big glass of white wine and 1 litre of water. Add a pinch of coarse salt and pepper.
Bring to the boil, then reduce the heat and let the fumet reduce, uncovered, for one hour.
Strain into a container.