Heat 2 tbsp of olive oil in a large saucepan. Add finely chopped red onion and cook for a few minutes until it becomes soft and transparent.
Add the canned tomatoes, frozen spinach, dried oregano and basil. Pour around 3 cups of chicken or vegetable stock. Alternative you can use water and 1 cube of chicken or vegetable stock. Season with salt and pepper. Bring the soup to boil and let simmer for a few minutes.
Add the tortellini to the soup and cook for about 5 minutes (check the exact cooking time on the package) until the tortellini are ready. Serve immediately.