Heat the oil in a large frying pan or wok, and add the onion, garlic, spring onions and leek. Cook over a medium-low heat for around 5 minutes, until the vegetables are soft. Add the rice, and cook for a further 2-3 minutes.
Next, add the vegetable stock and oregano. Mix well, and leave to simmer gently over a fairly low heat, stirring every few minutes. The rice will absorb the stock, and any excess moisture will disappear. At this point, check that the rice is fully cooked - add a dash more water if not, and cook for a few more minutes.
When the rice is cooked and there is no more excess water, add the fresh parsley and pine nuts, and season to taste.