Chef's Spicy Dip Sparks Terror Raid   A pot of burning chillies sparked fears of a chemical attack on a busy shopping street, recently. Police closed off three roads and evacuated homes in central London as a cloud of noxious smoke filled the air. But the source turned out to be some fiery food left cooking on a restaurant stove. Firefighters wearing protective breathing apparatus were called to D'Arblay Street, Soho as members of the public were shepherded away. The specialist crews then broke down the door of the Thai Cottage restaurant. They emerged around 7pm with a 9lb pot of chillies. Staff at the restaurant said they were surprised by the reaction of the emergency services. Chef Chalemchai Tangjariyapoon told The Times: "I was making a spicy dip with extra-hot chillies that are deliberately burnt. "To us it smells like burnt chilli and it is slightly unusual. I can understand why people who weren't Thai would not know what it was. But it doesn't smell like chemicals. I'm a bit confused." He was preparing Nam Prik Pao, a red-hot Thai dip served with prawn crackers, the paper said. The dip is prepared with garlic, shrimp paste, dried shrimp and vegetable oil. A Scotland Yard spokesman said: "The street was closed off for three hours while we were trying to discover the source of the odour."