Place two tablespoonfuls of raw mirepoix (No. 138) in a saucepan with one ounce of butter ; cook on a moderate fire for five minutes, then add two tablespoonfuls of flour, brown all well. Select one quart of well-washed, ripe, sound, fresh tomatoes, cut them into quarters, and plunge them into the saucepan with the rest, stirring briskly with a wooden spoon until they boil. Season with a good pinch of salt, half a pinch of pepper, and half a teaspoonful of powdered sugar. Boil the whole for forty-five minutes, then strain through a sieve into a vessel, and use when needed. This sauce can also be made with canned tomatoes, in which case cook them for only thirty minutes.