Heat olive oil in a saucepan and sauté onion and garlic until soft and fragrant.
Add chopped tomatoes and cook for 5–7 minutes until they soften.
Add basil leaves and vegetable stock.
Simmer for 10–12 minutes.
Blend until smooth using a blender or immersion blender.
Return the soup to the pan, season with salt, pepper, and oregano, then simmer for another 2–3 minutes.
Garnish with fresh basil and black pepper before serving.