Mix together water, beef powder, and Worchester sauce. Bring to boil. Sauté onions, butter and sugar until medium brown. To onions add flour salt and pepper. Cook for approx. 5 minutes. Add onions to broth and simmer for 20 minutes. Pour soup into bowls. Top with 1 slice of toast and sliced cheese. Place under broiler till cheese bubbles and is slightly brown.