Season the chuck roast pieces with salt and pepper. Heat 1 tbsp of olive oil in a Dutch oven over high heat until hot. Add half of the beef and sear until the beef has nice color. You’re not looking to cook the beef through, just to get some nice color on it. Should take about 5-7 minutes.
Remove the first half of the beef to a bowl once it’s seared. Add 1 more tbsp of oil to the pot and add the second half of the beef. Cook until the beef has some nice color. Remove the second half of beef to the bowl.
Lower the heat to medium-high and add the remaining 1 tbsp of olive oil to the pot. Add the carrots and onions and cook until they start to soften, about 5 minutes. Add the pancetta and cook until the pancetta starts to crisp a little, about 5 minutes.
Now add the garlic and cook until fragrant, about 30 seconds. Add the flour. Stir frequently for one minute to cook the flour and then add the tomato paste. Stir well and let the tomato paste cook for a minute.
Add the Guinness beer. Let it bubble and cook down for a couple of minutes. Then add the beef broth, bay leaf, thyme, salt, pepper, Worcestershire sauce, and sugar. Stir well and then add the beef back to the pot.
Bring to a boil, lower the heat to low, and cover with a lid. Cook for 2 hours, stirring occasionally, until the beef is tender and the stew has reduced.
After 2 hours, skim some of the fat off the top of the stew. Add the potatoes and the cornstarch slurry. Stir well and cover with the lid. Cook for another 30-40 minutes until the stew has thickened and the potatoes are fork-tender.
Taste for seasoning, adding more salt or pepper if necessary. Serve with a nice slice of crusty bread on the side. Enjoy!