Heat olive oil in a large pot over medium heat. Add onion and cook until softened, about 5 minutes.

Add garlic and cook for 1 minute more.

Stir in tomato paste, oregano, salt, and pepper.

Pour in vegetable broth and bring to a boil.

Reduce heat and simmer for 20 minutes, stirring occasionally.

Use an immersion blender to blend the soup until smooth.

Serve hot.