Sprinkle beef or veal cubes with salt and pepper. Heat fat in a 2-quart stew pot and brown seasoned meat in it. Add diced onion and continue cooking over low heat until onion is soft and golden. Add paprika and sauté three or four minutes. Sprinkle with flour and stir until flour is absorbed. Add canned tomatoes with their liquid, and hot water or beef stock. Cover pot, bring to a boil, then reduce heat so stew simmers gently. After 45 minutes add onions, carrots and potatoes and simmer another 30 to 40 minutes, or until vegetables are done. Add green peas for last 10 minutes of cooking time. Season if necessary with more salt and pepper and serve.