Leave the dried mushrooms to steep in cold water for a couple of hours.

Strain the liquid and set aside.

Lightly roast the rehydrated mushrooms along with the fresh or frozen porcini mushrooms, add the tomato paste, and keep cooking for about 3 minutes.

Add the mushroom-infused water, bring it to a boil, then reduce the liquid by half.

Get rid of any impurities on the surface.

Once the liquid has reduced, strain again and keep only the liquid.

Bring the liquid back to a boil, add the soy sauce, and reduce again by half.

Add the butter over low heat to thicken the sauce and serve it on your best dishes!