Whether or not this sauce is of Spanish origin, it has been adopted for centuries in France, is one of the basic sauces, and is the foundation of many other sauces and dishes.
Cut the vegetables in dice, put the butter in a saucepan and, when melted, add the vegetables. Simmer gently till the vegetables are slightly coloured, then add the flour, mix well with a wooden spoon, and simmer gently till the flour begins to brown. Then add very gradually the white wine and the stock. Bring to the boil, add the mushrooms and the tomato purée, and simmer very gently for 1 hour, skimming carefully as the scum rises.
Now strain into another saucepan through a sieve, replace on the fire, bring to the boil and again skim most carefully, as the sauce should be entirely free from grease. When finished, the sauce should be reduced to