Place the oil, butter and onions in a deep pan or pressure cooker, and put over medium heat.
Add the minced meat and stir-fry until brown, stirring frequently for about 5 minutes.
Then add the tomatoes, garlic and vegetables except the pepper and stir for a further 5 minutes.
Add the stock and heat it almost to boiling point then hold it warm. Heat the saffron threads in a small skillet for a minute, just until dry enough to crumble. Crush them and add them to the warm stock.
Add the washed rice, bay leaves and chopped fresh pepper, stirring only once and taste test it for salt. Adjust seasoning as desired.
Cover the rice, reduce the heat to low, and simmer gently and undisturbed for about 25 minutes, or until the liquid is absorbed and the rice is tender.
Fluff the rice with a fork and serve hot with a sprinkle of greens for garnish.