4 3-ounce turkey breast fillets (each about 1/4 inch thick)
2 tablespoons (1/4 stick) butter
12 ounces fresh assorted wild mushrooms (such as oyster, crimini, and stemmed shiitake), sliced
1/4 cup finely chopped shallots
1/2 cup low-salt chicken broth
2 tablespoons dry Sherry
2 tablespoons chopped fresh tarragon
Sprinkle turkey fillets with salt and pepper. Melt 1 tablespoon butter in large nonstick skillet over medium-high heat. Add turkey and cook until golden and cooked through, about 2 minutes per side. Transfer turkey to 2 plates. Tent with foil to keep warm.
Melt remaining 1 tablespoon butter in same skillet over medium-high heat. Add mushrooms and shallots; stir to blend. Cover and cook until mushrooms soften and release juices, about 5 minutes. Uncover and sauté until tender, about 2 minutes longer. Stir in chicken broth, Sherry, and half of tarragon. Boil until thickened to sauce consistency, scraping up browned bits, about 2 minutes. Spoon mushroom sauce over turkey. Sprinkle with remaining tarragon and serve.