Heat oil in a large pot or Dutch oven over medium-high heat; coat beef in flour and cook until well browned.
Pour beef stock, water and tomato paste into the pot; stir in rosemary, parsley, and pepper. Bring to a boil; reduce heat to low, add cubed potatoes and onion, cover and simmer for 1 hour. Stir green beans, mixed vegetables, celery, onion.
Dissolve cornstarch in 2 teaspoons of cold water; stir into stew. Cover and simmer until beef is tender, about 1 hour.