Heat the olive oil in a large pot over medium heat. Add the onion, carrot, celery, and garlic. Cook for 15 minutes, stirring occasionally, until the vegetables are softened.
Stir in the canned tomatoes, season with oregano, salt, and pepper and cook for 2–3 minutes until fragrant.
Pour in the vegetable broth and the orzo, bring to a boil, then reduce the heat to a simmer and cook for 7–8 minutes, or until the orzo is al dente.
Add the shrimp to the pot and cook for 3–4 minutes, or until they turn pink and opaque.
Remove the pot from the heat and stir in the fresh dill and red wine vinegar. Ladle the soup into bowls and serve with extra dill.
Notes
Storage: Kept in the fridge in an airtight container, the soup will keep 3-4 days. To reheat it, you can do so in a pot over low heat or in the microwave for 2-3 minutes.