In a medium bowl toss together the cheese and flour; set aside. In a small saucepan cook onion in hot margarine over medium heat until tender. Add broth, half of the apple, the cooked rice, beer, and white pepper.
Bring to boiling; reduce heat. Simmer, uncovered, for 10 minutes. Reduce heat to low. Slowly stir in cheese until melted. Stir in half-and-half; heat through.
To serve, divide the soup between 2 warm soup bowls. Sprinkle with the remaining apple.