Season the beef cubes generously with salt and freshly ground black pepper. Add the vegetable oil to a heavy-bottomed Dutch oven over high heat. When the oil is shimmering, add the beef cubes in small batches, turning occasionally, so that at least two sides develop a deep-brown sear. Repeat until all meat has been seared, lowering heat and adding additional oil if necessary between batches; remove meat and set aside.
Reduce heat to medium and add the onions, carrots, and celery. Saute until translucent and soft, about 5 minutes. Add the garlic, bay leaves, barley, and herbs; saute an additional 2 minutes.
Add the wine to deglaze the pan, stirring with a wooden spoon (scrape the bottom of the pan as the wine cooks down). Allow the wine to reduce by half.
Pour the mixture into a slow-cooker. Add the meat and any accumulated juices. Stir in the stock. Set slow-cooker on low and leave for 8 hours.
If you are using potatoes, add them in during the final hour of cooking (adjust slow-cooker temperature to high). Alternatively, you can steam the potatoes until tender and add them to the soup during the final 10 minutes of cooking.
Taste the soup, adjusting seasoning as necessary with S&P. Garnish with parsley and grated cheese. Enjoy!