Simmer all ingredients until thick. Garnish with plain yogurt. TO COOK BEANS: Rinse beans. Cook 2 cups beans in 5 cups water. Bring water to a boil. Add beans. Turn temperature to low or simmer. Cover with heavy lid. Simmer 2 to 3 hours until tender. DO NOT season until beans are done. VARIATION: Saute chopped green peppers, 2 finely chopped garlic cloves, 2 stalks of celery chopped, until barely tender. Add to soup and simmer.