George Tsioros—proprietor of the Olympic Food and Cheese Mart in Toronto’s St. Lawrence Market—can tell you the story of his life in a sentence, which is a small miracle of brevity when you consider that he was born in Greece, that he is now 64 years old, that he has run his own business since age 18 and that he has more than 600 different cheeses packed into his 75-square-metre (800-square-foot) shop, some of which sell for $100 a kilogram. “I came to Canada when I was 16,” he says. “I got off the boat in Montreal, caught a train to Toronto, went to the home of my sister and brother-in-law, and the next day I was in the market.” That was on Nov. 22, 1960, and he’s been there ever since. His sister and her husband owned a meat store, and the teenaged Tsioros worked part time for the...