Heat the olive oil in a large heavy-bottomed pot over medium-high heat. Once the oil is shimmering, add the diced beef and season generously with salt and pepper. Sear the beef cubes for about 5-7 minutes, turning occasionally, until they are browned on all sides. Once browned, remove the beef from the pot and set aside.
In the same pot, add the chopped onion, minced garlic, diced carrots, and diced celery. Sauté the mixture for about 4-5 minutes until the vegetables soften and the onions become translucent.
Stir in the rinsed pearl barley and cook for an additional 1-2 minutes, allowing the barley to toast lightly and absorb some flavors.
Return the browned beef to the pot and pour in the beef broth. Add the dried thyme and bay leaf, then bring the mixture to a rolling boil. After it reaches a boil, reduce the heat to low and let the soup simmer gently.
Cover the pot and allow the soup to simmer for approximately 1 hour, stirring occasionally. The beef should become tender and the barley nicely cooked through.
In the final 10 minutes of cooking, incorporate the green peas to warm them through. Before serving, be sure to remove the bay leaf from the soup.
Taste the soup and adjust seasoning by adding more salt and pepper if desired.
Serve the soup hot by ladling it into deep bowls, and finish with a sprinkle of fresh parsley for a burst of color and flavor.
Notes
For an appealing presentation, serve the soup in deep bowls accompanied by crusty bread for dipping.