1. Saute onions and garlic in butter for about 3 minutes.
2. Stir in flour until well blended.
3. Gradually add broth and bring to a boil.
4. Cook and stir about 2 minutes, until thickened.
5. Reduce heat, simmer for 15 minutes.
6. Add cayenne.
7. You can also add cooked rice to this soup for a different version.