Heat a pot over medium heat, and add oil. When oil is shimmering, add bacon and sauté bacon pieces until lightly browned about 5 minutes. Transfer bacon with a slotted spoon to a medium bowl and reserve bacon fat in the pot.

Dry the beef thoroughly with paper towels and season with salt and pepper. Working in batches to avoid crowding the pot, add the beef to the pot and sear, turning as needed, until very nicely browned on all sides. Transfer seared beef to the bowl with bacon. Reduce heat to low and add the carrot and onion; sauté until lightly browned, about 8 minutes.

Return the beef and bacon to the pot; season lightly with salt and pepper. Sprinkle flour over and toss to lightly coat. Slowly stir in wine and add enough broth to just cover the meat. Stir in tomato paste, garlic, thyme sprigs, and bay leaves. Cover with a lid and bring to a simmer for 45 minutes to 1 hour, or more as needed.

To a large ovenproof skillet over medium-high heat, add butter. Saute the mushrooms and pearl onions. Drizzle with sherry vinegar and season generously with salt and pepper. Cook, stirring often until the vegetables are tender and have developed caramelization, about 8 minutes. Then set aside.

Once the beef is simmering, make the mashed potatoes. Peel and cut potatoes into bite-sized chunks so they all cook evenly.

Place in a pot with cold water over high heat. Once boiling, turn the heat down to a simmer.

In a saucepan, melt the butter. Once the butter is melted, stir in the cream to warm and then remove from the heat and set aside.

Check the potatoes by inserting a fork into them; once the fork slides in and out with ease, take off the heat and strain out all of the water.

Mash the potatoes with a fork or potato ricer. Slowly add in the cream and butter mixture and whip until smooth. Season with salt and pepper to taste.

Once the beef is tender, discard thyme and bay leaves. Using a ladle, skim the fat off the top. Increase the heat to medium-high, and bring to a rapid simmer to reduce the braising liquid. Add the sautéed onions and mushrooms. Continue simmering until the liquid reduces and is thick enough to coat the back of a spoon. Taste and adjust the seasoning with salt and pepper. Stir in the parsley.

Toast and butter the bread.

To serve: Portion the bourguignon into bowls, and serve with mashed potatoes, bread, and sparkling water. Garnish with rosemary.