Preparation Heat oil in heavy medium saucepan over medium heat. Add onion and three garlic clover and sauté until tender, about 5 minutes. Stir in 1 tablespoon chili powder and cook 1 minute longer. Add tomatoes with their juices and beef broth. Cover and simmer 5 minutes. Puree mixture in blender or processor in batches; return to saucepan. Season beef with salt and pepper. Mix in remaining garlic clove, 1/2 tablespoon chili powder and oregano. Form beef into 1-inch meatballs. Return soup to gentle simmer. Add meatballs to soup and simmer until meatballs are just cooked through, about 5 minutes. Ladle soup into bowls. Garnish soup with chopped fresh cilantro and serve with sour cream if desired.
Preparation Heat oil in heavy medium saucepan over medium heat. Add onion and three garlic clover and sauté until tender, about 5 minutes. Stir in 1 tablespoon chili powder and cook 1 minute longer. Add tomatoes with their juices and beef broth. Cover and simmer 5 minutes. Puree mixture in blender or processor in batches; return to saucepan. Season beef with salt and pepper. Mix in remaining garlic clove, 1/2 tablespoon chili powder and oregano. Form beef into 1-inch meatballs. Return soup to gentle simmer. Add meatballs to soup and simmer until meatballs are just cooked through, about 5 minutes. Ladle soup into bowls. Garnish soup with chopped fresh cilantro and serve with sour cream if desired.