On Wednesday night, dozens of pizzaiolos crammed into the kitchen of La Sorted’s in Chinatown to make hundreds of meals for a newly formed food-relief coalition: the L.A. Pizza Alliance.

17 January marks World Pizza Day, a celebration of a dish with more than 2,000 years of history. From Neapolitan and Roman styles to Margherita, diavola, and even potato-topped variations ...