Cut the beef chuck roast into 1-inch cubes. Heat a large pot on high (cast iron works best). Add 1 tablespoon oil. Once the pot is hot, add a single, spaced-out layer of beef (don’t overcrowd). Season with salt & pepper. Sear for about 2 minutes per side. Don’t stir; let each side brown, then flip with tongs only when it releases easily.
Sear the beef in batches as needed, adding more oil only if the pot gets dry. Transfer each browned batch directly into the slow cooker.
Add the remaining 1 tablespoon oil to the pot, then add the diced onion. Sauté, scraping up any browned bits, until the onion is golden and tender, about 5 minutes. Transfer to the slow cooker.
Add all remaining ingredients to the slow cooker and stir to combine. Make sure everything is submerged in the liquid.
Cover and cook on low for 7 to 10 hours or on high for 5 to 8 hours, until the beef and potatoes are very tender. Cooking on low gives the best texture.
Before serving, remove the bay leaves, taste and adjust seasonings (I typically add another 1/2 tsp salt), stir well, and ladle into bowls. Enjoy!
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Notes
Storage: Refrigerate in an airtight container for up to 4 days. Barley keeps soaking up liquid, so if you want to avoid that, strain it out and store separately.Reheat: Warm gently on the stovetop, adding a splash of broth if it thickens.