Pat the beef cubes dry with a paper towel. In a bowl, toss the beef with flour, salt, and black pepper until evenly coated. Heat olive oil in a large skillet over medium-high heat. Add the beef in a single layer and sear for 2-3 minutes per side, until a deep brown crust forms. Transfer the seared beef to your crockpot.

In the same skillet, add the chopped onion and sauté for 3-4 minutes. Add the minced garlic and cook for another minute until fragrant. Pour in a splash of beef broth to deglaze the pan, scraping up all the browned bits. Pour this mixture into the crockpot.

Add the chopped carrots, celery, potatoes, beef broth, tomato paste, Worcestershire sauce, thyme, rosemary, and bay leaf to the crockpot. Stir to combine.

Cover and cook on low for 8-10 hours or on high for 4-5 hours, until the beef is tender.

Remove the bay leaf and herb sprigs. Stir in the frozen peas. If a thicker gravy is desired, mix 2 tablespoons of cornstarch with 3 tablespoons of cold water, stir into the stew, and cook on high for 15-20 minutes until thickened.