30-Minute Filet Bourguignonne with Mashed Potatoes

An earthy red wine like pinot noir is traditionally used in Burgundy, where the classic time-consuming stew was born. Serve the dish with mashed potatoes, as indicated in the recipe, or, if you prefer, with pasta pappardelle.
Put the potatoes in a saucepan over high heat; cover with cool water. Bring to a boil; cook for 10 minutes or until tender. Drain the water. Return the potatoes to the pan; keep warm.While the potatoes are cooking, place the onions in a microwave-safe bowl; cover with a paper towel. Reheat in the microwave on high power for 4 minutes. Finely chop 1 (2-inch) cube of tenderloin and set aside. Dry the remaining beef cubes with a paper towel; sprinkle evenly with 1/4 teaspoon salt and 1/4 teaspoon pepper.Heat a 12-inch diameter cast-iron skillet over medium-high heat. Melt 1 tablespoon of butter in a skillet; stir to coat. Add the seasoned beef cubes; simmer for 3 minutes, until browned on all sides. Remove the beef from the pan. Add the finely chopped beef and bacon to the pan; simmer for 3 minutes, stirring occasionally. Add the mushrooms; simmer for 5 minutes or until the mushrooms are lightly browned, stirring occasionally. Add the garlic, chopped thyme and sugar; simmer for 1 minute, stirring constantly. Add the tomato paste; cook for 1 minute, stirring constantly. Add the wine and bring to a boil, scraping off the pan so that the pieces are not browned. Cook for 2 minutes or until the liquid is reduced by half.Add the onion and stock; bring to a boil. Cook for 1 minute. Combine 2 tablespoons of water and flour in a bowl, stirring with a whisk until smooth. Add the flour mixture to the pan; cook for 1 minute, stirring constantly. Place the sauteed beef cubes in the skillet; cook for 2 minutes or until they are warmed through to medium-deep or the desired degree of roasting.Add the remaining 1/4 teaspoon salt, remaining 1/4 teaspoon pepper, remaining 2 teaspoons butter and milk to the potatoes in the pan; mash with a potato masher until desired consistency. Serve the beef with the sauce on top of the potatoes; garnish with thyme sprigs if desired.