In a medium stock pot over medium heat, melt butter and add onions. Sauté until soft and translucent, about 8 minutes. Add garlic and sauté for 2 more minutes, stirring constantly so garlic doesn't brown. Add crushed tomatoes and stir well. Cook uncovered over medium heat for 5 minutes, stirring occasionally. Turn off heat.

Transfer mixture to a blender in batches and purée until smooth. Add some of the chicken broth if purée is too thick to blend properly. Return puréed mixture to pot and heat over medium heat. Add chicken broth, tomato sauce, and sugar. Reduce heat to low and simmer for 15 minutes. Stir in basil and simmer for 5 minutes more. Remove soup from heat and whisk in yoghurt. Season with salt and white pepper to taste and serve immediately.

Makes 6 servings, about 1 cup each.

Click here to view the Next Recipe!