Preheat oven to 375 degrees. Heat oil in a non-stick pan. Cook onion until translucent, then add ground beef and cook until browned. Pour off any excess fat. Add flour and cook for an additional minute. Add chicken broth, ketchup and Worchestershire sauce. Bring mixture to a boil, then reduce heat and let simmer for five minutes. While meat and onion mixture is simmering, put carrots and peas in a microwave safe bowl, add 1/4 cup water, cover with seran wrap and cook in microwave until tender (about five minutes). Add to meat and onions when cooked. Spread mixture in the bottom of a greased 9 x 13 pan.
Bring additional water to a boil, and prepare mashed potatoes according to package directions. Spread over top of meat and vegetable mixture.