Melt butter in a saucepan over medium heat. Add onion and garlic, and cook, stirring until tender. Stir in the tomatoes and condensed chicken broth, and season with dill weed, salt, pepper and the bay leaf. Bring to a boil, then reduce heat and simmer for 45 minutes.
Remove from heat, and discard bay leaf. Use a food processor or blender to puree the soup in small batches until smooth. Serve immediately, or chill and serve cold.