In a large Dutch Oven or pot, over medium-high heat, heat the oil and add diced bacon. Cook until crispy, about 4-5 minutes, then remove it with a slotted spoon and set aside.
Season your cubed chuck roast generously with salt and pepper before adding it to the pot in batches, browning on all sides for about 1-2 minutes per side.
Reduce heat to medium, adding more oil if necessary, then stir in sliced onions and sauté until they start to brown—about 5 minutes—before adding minced garlic for an additional minute until fragrant.
Mix in flour and tomato paste until well combined; let it cook for a minute or two until darkened slightly before pouring in beef broth while scraping up any browned bits from the bottom of the pot.
Stir in additional beef broth along with Worcestershire sauce, brown sugar, salt, pepper, cooked bacon, thyme sprigs, and bring everything to a boil before reducing heat to simmer.
After one hour of simmering, add carrots and potatoes; cover again until both vegetables are tender and beef falls apart easily—approximately another hour of cooking time.