Peel the carrots, celery and shallots and dice them into small cubes.

Heat the oil in a large saucepan, add the vegetables and brown them on all sides. Stir gently so that everything browns nicely and the flavours develop.

Remove the stalks from the tomatoes, dice them finely and add them to the pan along with the tomato purée, mushrooms, spices and sugar. Leave to simmer for about 30 minutes, stirring frequently.

Once all the vegetable juice has evaporated, gradually add 6 dl of water to thin out the heavily reduced vegetable syrup. Allow the liquid to reduce completely several times.

Dust the vegetables with the flour and stir. Deglaze with the balsamic vinegar and allow to reduce slightly. Top up with the remaining water (approx. 2.4 l).

Add the sprigs of herbs and allow everything to simmer for about 1 hour. Pass the sauce through a sieve and, depending on the consistency, allow it to reduce a little further.