Persian beef fillet kebab (Kabab barg)

1. Slice the beef fillet along the grain into long strips 1 cm thick, then flatten under cling film with a meat mallet to half a centimetre.

2. Grate the onions, squeeze out the juice and mix it with the lemon juice, oil and pepper; turn the meat in it, cover and refrigerate for 2-4 hours.

3. Grind the saffron to a powder and steep in 2 tbsp hot water, then mix with the melted butter.

4. Thread the meat strips lengthways onto flat skewers in a wavy pattern and only now salt them.

5. Grill over very high heat for 2-3 minutes per side, brushing with the saffron butter.

6. Serve sprinkled with sumac, with saffron rice and grilled tomatoes.

Tip: "Barg" means leaf, referring to the thin, leaf-like strips of meat. If you don't flatten it thinly enough, the meat burns outside and stays raw inside. Always salt just before grilling, as salt in the marinade would draw out the juices.