1. To begin, combine the ground beef, ground lamb, breadcrumbs, parsley, Parmesan, egg, garlic, salt, pepper, and Worcestershire sauce in a large bowl. Mix until well-incorporated and shape into small meatballs, about 1-inch in size.

2. Heat olive oil in a large pot or Dutch oven over medium heat. Brown the meatballs on all sides for about 2-3 minutes per batch. Remove the meatballs from the pot and set aside.

3. In the same pot, add the diced onion, sliced carrots, and diced potatoes. Sauté for 5-6 minutes until they begin to soften. Stir in the tomato paste, dried thyme, and dried rosemary, letting the flavors meld for a minute or two.

4. Pour in the beef broth and bring to a simmer. Return the browned meatballs to the pot, cover, and let simmer for 30-35 minutes until the meatballs are cooked through and the potatoes are tender.

5. In the final minutes of cooking, stir in the frozen peas. Once heated through, serve the Irish Meatball Stew.