“When I went on Swedish TV and became and a celebrity chef in Sweden, I decided to quit,” he says, deadpan. “I didn’t want to be a celebrity.

He took an unlikely path to becoming a chef, much less a fishing nut and a tackle maker. As a kid, he fished with his grandfather some. But when he was 16, “the dark side took over,” he says.

The Swedish chef is reviving ancient techniques, ditching modern kitchens and embracing the raw power of open flames. At his London restaurant, that means flambadou-fired oysters, juniper-smoked ...