Cut the chuck roast into rough cubes. Season with an even sprinkling of salt and black pepper, then lightly dust with flour. Mix and add just enough flour until each piece is lightly coated.

Preheat a braising pot, add enough oil to coat the bottom of the surface, and sear the floured beef chunks until browned on all sides (work in batches, if necessary). Remove the browned beef pieces and set aside.

In the same pot, add the butter, bacon, sliced onions, and garlic cloves. Stir frequently over medium heat to begin to sweat everything. The bacon will render and the onions will begin to break down, deglazing the bottom of the pan.

Continue to sauté & stir this mixture until the onions have caramelized and become sweet & jammy (~45 minutes minimum, although you can go longer and further darken the onions). Supervise and scrape the bottom of the pot frequently to prevent burning (if needed, you can deglaze any dark spots with a splash of water).

Add the beer to the pot, deglaze anything on the bottom of the pan, bring to a simmer, and reduce by about half to concentrate the flavors (~ 5 mins).

Return the browned beef chunks to the pot, followed by the bay leaf, a spoonful of sugar, a splash of vinegar, and the thyme. Top with just enough beef stock until the meat is mostly submerged.

Partially cover the pot with a lid and braise for 4-6 hours until the meat is completely tender and the cooking liquid has reduced. You can do this on the stovetop or in a 300°F/150°C oven. If using the oven, optionally remove the lid completely during the last hour of cooking for extra browning.

When finished, taste and adjust with more salt, vinegar, or sugar, if needed.

Allow the braise to cool slightly, and serve with french fries, bread, or mashed potatoes. Garnish with minced parsley.