Rice Theory’s mix of low-commitment items, cute branding and bold flavors tempered by sushi rice have brought steady lines since Day 1.

Succulent, gently poached chicken, soothing soup, fragrant rice and a sparkly ginger-scallion sauce. What’s not to love?

To hear the cook, writer and teacher Sonoko Sakai tell it, “1955 is the year my mother was liberated.” Several things ...