Eatery with Jack and the bean stalk

Just opened last Friday by a husband/wife team, JATBB's Back Bay cart slings Italian sodas, frosted-to-order cupcakes (coconut cream cheese, vanilla, chocolate, etc), and signature bowls chock full o' black beans, brown rice, avocado, cheddar, salsa, sour cream, cilantro, and a choice of a smoky chipotle-lime or a creamy lemon sauce, which you would certainly not opt for if their spokesperson was Robert Plant.