Soak barberries in warm water for ten min, drain and fry briefly in a frying pan with hot clarified butter.
Rinse long grain rice well in cold water on a sieve, cook in salted water for 4 min, then rinse repeatedly when cooled. Put clarified butter in the saucepan, place the drained long-grain rice on top in a pyramid shape, cover with a folded dishcloth, cover with a closed lid and cook over a mild heat until done.
Dissolve saffron with warm water. Season the long-grain rice with salt and pepper, stir in the saffron and place on a warmed plate. Sprinkle barberries on top.
By the way: Did you know that clarified butter is obtained by extracting water, milk protein and lactose from butter?