El Indio (San Diego, Calif.) • Charlie's Diner (Spencer, Mass.) • Paradise Pup (Des Plaines, Ill.)Stops include a Mexican restaurant and tortilla factory in San Diego where father and daughter work side-by-side. A Massachusetts diner where father and son have been working together for 20 years. And a legendary Chicago burger joint where two brothers turn out for char-burgers and three-layer fries.