Booranis are a variety of yogurt-based dishes that are served as sides in Iran. They are cousins of mutabal, where yogurt is used instead of tahini. You can use any kind of green or vegetable instead of the spinach.
Heat half the oil in a heavy-based frying pan over a medium heat. Add the shallots and fry for 8–10 minutes until soft and lightly golden. Transfer to a plate and set aside. Add the remaining oil to the pan and cook the sliced onion, if using, until golden and crispy. Set aside.
Meanwhile, put the spinach in a large saucepan and pour in