In a large bowl, season the beef cubes with salt and pepper. Heat the olive oil in a large skillet over medium-high heat. Brown the beef in batches, about 5 minutes per batch, then transfer to the slow cooker.

In the same skillet, add the chopped onion and garlic. Sauté for 2-3 minutes until softened, then add to the slow cooker.

Add the carrots, potatoes, beef broth, Worcestershire sauce, thyme, rosemary, and bay leaf to the slow cooker. Stir to combine.

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

If you prefer a thicker stew, mix the cornstarch with water in a small bowl to create a slurry. Stir it into the stew during the last 30 minutes of cooking.

About 10 minutes before serving, stir in the frozen peas. Remove the bay leaf before serving.