Cube the beef and pat dry with paper towels. Generously salt and pepper all the sides.
Heat 1 tablespoon oil in a large pan or pot over medium-high heat, and once shimmering, add beef cubes in an even layer (you can do this in batches to not overcrowd the meat). Sear for about 15–20 seconds per side (about 1 minute total) and transfer beef to a large slow cooker.
Turn heat down to medium-low and add remaining 2 tablespoons olive oil. Add onion and sauté for 2 minutes. Add garlic and sauté for 30 seconds. Add carrots and celery and continue to sauté, stirring occasionally for 5–8 minutes.
Turn heat to high, add 1-1/2 cups of beef stock (or red wine), and scrape any browned bits up from the pan. Stir and simmer for 3 minutes, then pour the veggie mixture into the crockpot.
While the veggies are simmering, you can add everything else to the crockpot: tomato paste, chopped potatoes, crumbled beef bouillon cubes, Worcestershire sauce, fresh thyme, bay leaves, uncooked pearl barley, sugar, dried basil, dried oregano, undrained fire-roasted tomatoes, and the rest of the beef stock.
Stir to combine. Cover and cook on low for 7–8 hours or on high for 4–5 hours.
Remove bay leaves and taste for seasoning. It will vary greatly depending on the beef stock and bouillon cubes you use; I generally add about 1/2 teaspoon salt and 1/4 teaspoon pepper.
Enjoy with fresh parsley (optional) and a hearty loaf of bread!
Notes
Note 1: If you like to cook with wine, you can swap out 1 1/2 cups of red wine for that amount of beef stock in step 4. The remaining 7 cups of beef stock will be added in step 5.Note 2:Here are the beef bouillon cubes I use. Also, if you’re worried about sodium/salt from the cubes and stock, you can omit the cubes (or add, crumbled in small amounts, later to taste).Storage: Transfer to an airtight container and refrigerate for up to 4 days.Freezing: Place in a freezer-safe container or freezer bag, leaving a bit of room at the top for expansion. Freeze for up to 3 months.