Put oil in a large saucepan and heat. Add onions, beef base, red wine, salt and pepper. Cook until the onions are tender, but still somewhat crisp. Add water. Bring to a boil and then simmer for 10 minutes.
Lightly toast the bread. Place one slice of bread in each bowl and cover with a slice of cheese. Sprinkle lightly with Parmesan cheese and place in the broiler until the cheese is melted and browning on top. Serve immediately.