Peel potatoes and cut them into large pieces, place in a pot with water and cover with lid. Bring to a boil. Reduce heat; cover and cook for 10-15 minutes or until tender. Drain.
Meanwhile, in a large skillet, cook beef and onion over medium heat until meat is no longer pink; drain. Stir in the cabbage, carrots, thyme, and Worcestershire sauce.
In a small bowl, combine the flour, tomato paste and broth until smooth. Gradually stir into meat mixture. Bring to a boil. Reduce heat; cover and simmer for 15-20 minutes or until vegetables are tender. Stir in the peas, salt, and pepper.
Drain potatoes, mash with milk, butter, and the remaining salt and pepper. Serve with meat mixture.