Preheat oven to 400 degrees F.

Toss mushrooms, garlic, 1 tablespoon oil, 1/4 teaspoon pepper, 1 teaspoon sage, 1 teaspoon thyme and 1/2 teaspoon salt in a large bowl. Transfer to a roasting pan and roast in the oven for 5 minutes. Stir and continue roasting until the mushrooms are soft and fragrant, 5 to 10 minutes more. Set aside to cool.

To butterfly tenderloins, lay one tenderloin on a large cutting board. Holding the knife blade flat, parallel to the board, make a lengthwise cut through the center of the meat, stopping short of the opposite edge so that the flaps remain attached. Open up the flaps as you would open a book. Cover with plastic wrap. With a meat pounder, rolling pin or heavy pan, pound the meat to an even 1/4-inch thickness. Butterfly and pound the remaining tenderloin.

Divide the mushroom mixture between the tenderloins, spreading evenly and leaving a 1-inch border all around. Starting with a long side, roll up each tenderloin to enclose the filling, then tie the roasts at 2-inch intervals with kitchen string. Combine the remaining 2 teaspoons pepper, 1 teaspoon sage, 1 teaspoon thyme and 1 teaspoon salt in a small bowl. Rub the mixture all over the tenderloins.

Increase oven temperature to 450 degrees F.

Heat the remaining 1 tablespoon oil in a large, heavy, ovenproof skillet over medium-high heat. Add the roasts, bending to fit if necessary, and cook, turning often, until the outsides are browned, 3 to 5 minutes total.

Transfer the pan to the oven and roast, checking often, until the internal temperature reaches 145 degrees F , 15 to 20 minutes. Transfer the roasts to a cutting board, tent with foil and let rest for 5 minutes. Remove the string, cut the pork into 1-inch-thick slices and serve with Tomato Salsa Verde on the side.

Substitution Tip: Not all of us will have fresh porcinis at the ready, so you may substitute an equal amount of cremini, portobello or shiitake mushrooms. If you are using fresh shiitakes, remove and discard the stems first because they are too tough and fibrous to use.

MAKE AHEAD TIP: Equipment: Kitchen string