Even without the rhubarb, tomato dumplings are a mystery to those who didn’t grow up eating them. They are an old-fashioned favorite of some grandmas and meat-and-three diners. Juicy canned tomatoes, either home-canned or store-bought, simmer in a fragrant stew that is topped with dollops of biscuit dough that poach in the delicious liquid. Think of them as chicken and dumplings, made with tomatoes instead of chicken.