A few years ago, while chatting with a friend that doesn't eat sweets, chef Heidi Hamamura accepted a challenge that would change the way St. Louisans celebrate their birthdays.
"She said to me, 'It would be so baller if you could make me a sushi cake,' so I told her I was going to make her one," Hamamura says. "I used to make sushi pizzas at my dad's restaurant [Sansui] and have made sushi in the shape of Christmas sweaters and menorahs.…