It was exactly 5 a.m. and inside, Hassan Najjar, a burly man with a thick gold necklace over his hairy chest, was stirring a giant pot filled with a soup of cooked sheep’s heads, brains and hooves. Two waiters, known to everyone as Issa and Mohsen, were busy filling baskets with special bread baked in a stone oven. Pots of tea seemed to be perpetually boiling. The restaurant, a tiny space with blue marble counters where customers stand and eat, specializes in kaleh pache, or “heads and hooves” soup, the most traditional of Iranian breakfast dishes. Its popularity is under threat, however, from the spread of fast food and from doctors warning about the dish’s high cholesterol.