Heat olive oil in a large pot over medium-high heat. Add onion, garlic, salt and pepper and sauté for 5 minutes.
Meanwhile, place tomato paste, diced tomatoes, garlic powder, dried basil and sugar in a blender and blend until smooth.
Add cooked onions and garlic mixture to the blender and blend until smooth (You could also add the tomato mixture to the pot and use an immersion blender if you don’t have a blender large enough).
Pour mixture from the blender into the pot over medium-high heat. Bring the soup to a boil then reduce heat to low and add chicken broth and yogurt and mix until well combined.
Ladle into bowls and serve.