Put the veal bones into a roasting tin and brown them in a preheated oven, 200°C/400°F (gas mark 6), for about 30 minutes, turning once. Transfer to a large pan. Cook the onion, carrots, celery and garlic in the same roasting pan for a few minutes, but without browning. Then over a direct heat stir in the wine and allow to bubble until reduced by half. Tip the vegetables and reduced liquid into the pan with the bones. Cover with the water, bring to the boil, then reduce the heat and simmer, skimming off any fat or scum from the surface.
Add the bouquet garni and allow to simmer very gently for 2–3 hours. Cool slightly, then strain through a very fine sieve. Cool, refrigerate and use within 2 days, or freeze and keep for up to 3 months.