I didn’t see it coming, that mild feeling of electric currents buzzing on my tongue as if I’d licked a battery. Seated on a busy pavement in front of a lazy Susan weighed down with sizzling hotpot, diced rabbit and fish soup, I was digging into a spicy meal on the humid first night of a visit to Chengdu, the capital of China’s south-western Sichuan province and the cradle of the region’s famously fiery cuisine. The plates resembled volcanic islands, each dish’s contents swimming in chilli oil hidden beneath a red-hot mountain of peppers and garlic. Tongue ablaze and face...