Chop the mushrooms finely, either by hand or in a food processor, so that they end up in coarse fragments rather than fine pieces, 1/8 inch or so long. Press down on the olives to break out the pits or, if this doesn’t seem to work (this is a little harder with green olives than with black), slice away the flesh with a paring knife and chop them slightly finer than the mushrooms.

Heat the butter and oil in a skillet and add the onion, oregano, parsley, and mushrooms. Salt lightly and cook over brisk heat, stirring constantly, for 5 or 6 minutes. The mushrooms should start to color a little and the onions soften. Add the garlic during the last few minutes of cooking so that it doesn’t burn. Season with pepper and set aside to cool before filling the ravioli.

Layout 16 wonton skins. Heap 2 to 3 teaspoons of filling neatly into the center of the squares, then paint the edges with water and cover securely with the top pieces of dough. Firmly press the sides together, squeeze out any air, and cut with a ravioli crimper to secure. Set the ravioli aside on a tray dusted with flour, cover, and refrigerate until ready to use. Make the sauce below.

To cook the ravioli, slip them into gently boiling salted water and simmer until the edges of the squares are done and they rise to the surface, about 3 to 5 minutes. Serve in warm pasta plates with the sauce and a grating of Parmigiano-Reggiano.

For the sauce:

Cover the dried mushrooms with the hot water and set them aside to soak while you prepare all the other ingredients. When you’re ready to use them, run your fingers over the mushrooms to loosen any hidden sand, then pour the soaking water through a paper towel.

Heat the butter and oil in a wide skillet or a saucepan and add the onion, dried herbs, parsley, fresh mushrooms, and garlic. Cook over medium-high heat, stirring frequently, for about 5 minutes. Add salt to taste and continue cooking until the onions begin to color a little, another few minutes.

Add another 2 teaspoons butter to the pan. Stir in the flour, working it into the vegetables as well as you can; the whole mass will be quite thick, and the pan will become very dry. Next pour in the red wine, bring it to a boil, and let it reduce for a few minutes. Stir in the mustard and tomato paste and pour in the mushrooms and their soaking water. Bring to a boil and cover the pan; then lower the heat and simmer slowly for 25 minutes. Strain and season to taste with salt and pepper.

This sauce would also be good with other pasta or rice.