1. Heat oven to 425°F. Season tenderloins with salt and pepper.
2. Heat large oven-proof skillet over medium; add oil. Sear tenderloins on 1 side for 4 minutes. Turn to second side and place pan in oven; roast 4 minutes. Turn to third side; roast another 4 minutes. If internal temperature has not reached 145°F to 160°F, turn to fourth side and roast until it does. Remove tenderloins from skillet and let stand 10 minutes before slicing.
3. Add sherry to deglaze skillet over medium-high heat, scraping browned bits from bottom of pan. Cook until sherry has almost completely evaporated.
4. Add pickled mushrooms with liquid; cook until liquid has almost completely evaporated. Add stock; cook and stir until reduced by half. Stir in butter and parsley and chives; season with salt and pepper to taste. Keep warm.

Pickled Mushrooms
3 cups champagne or white wine vinegar
1 cup water
1 cup sugar
1 teaspoon salt
3 shallots, sliced
4 lbs. button mushrooms, quartered
1/2 cup olive oil

1. Combine vinegar, water, sugar, salt and shallots in saucepan; bring to a boil over medium-high heat.
2. Toss mushrooms with olive oil. Roast in large hot skillet for 2 minutes over medium-high heat.
3. Combine mushrooms with hot brine in non-metallic container, cool. Cover and refrigerate. Store leftovers in refrigerator.

Honey & Thyme Roasted Chestnuts
1 lb. frozen shelled and peeled chestnuts, thawed
2 tablespoons butter
1 shallot, peeled and minced
1 tablespoon chopped fresh thyme
3 tablespoons honey
Salt and pepper

1. Place chestnuts in saucepan; add water until nuts are just covered. Bring to a boil over medium-high heat. Reduce heat and simmer until tender, about 10 minutes; drain.
2. Heat large skillet over medium-high. Add butter, shallot and thyme; sauté until shallot starts to soften. Add chestnuts; cook and stir 2 minutes. Remove from heat
3. Drizzle honey over chestnuts; toss to coat. Season with salt and pepper to taste.
4. To serve, arrange chestnuts on platter with sliced tenderloins, spoon sauce over top.