In a stockpot, cook bacon over medium heat until crisp. Using a slotted spoon, remove to paper towels. In a large shallow dish, combine flour, salt and pepper. Add beef, a few pieces at a time, and turn to coat. Brown beef in the bacon drippings. Remove and set aside., In the same pot, saute the mushrooms, leeks, carrots and celery in oil until tender. Add garlic; cook 1 minute longer. Stir in tomato paste until blended. Add the broth, beer, bay leaves, thyme, parsley and rosemary. Return beef and bacon to pot. Bring to a boil. Reduce heat; cover and simmer until beef is tender, about 2 hours., Add potatoes. Return to a boil. Reduce heat; cover and simmer until potatoes are tender, about 1 hour longer. Combine cornstarch and water until smooth; stir into stew. Bring to a boil; cook and stir until thickened, about 2 minutes. Add peas; heat through. Discard bay leaves.