Heat the olive oil in a large saucepan. Add the onion and cook for 5 minutes until soft.
Add the garlic and oregano, cook for 1 minute until fragrant.
Pour in the chopped tomatoes, sugar and vegetable stock. Bring to a simmer.
Add the orzo pasta and cook for 8-10 minutes until the pasta is tender, stirring occasionally so the orzo does not stick to the bottom.
Season with salt and pepper. The pasta will have thickened the soup into a hearty, bowl-filling meal.
Serve in warm bowls with a drizzle of olive oil, fresh herbs and parmesan if you have them.