For the mushroom sauce: In a skillet with oil, saute mushrooms until tender. Add garlic and allow to brown lightly. Deglaze the skillet with cabernet sauvignon and reduce by three-fourths. Add veal stock and reduce by half. Add thyme and finish with butter. Season with salt and pepper. Keep warm until ready to serve.

For the potatoes: Place potatoes in a stockpot with lukewarm water to cover and bring to a boil. Reduce to a simmer and skim the foam off the top. Cook until tender. In a saucepot, heat cream and butter while potatoes are cooking. Drain water from potatoes and put through a sieve, add butter and cream and season with salt and pepper. Whip vigorously.

Preheat the grill to medium high. Roll the fillet in salt and pepper. Massage meat with olive oil. Grill to desired degree of doneness, about 130 degrees F for medium when taken on an instant read thermometer.