“The slices are just the right size, and they use a natural casing,” Mr. Grossman said. When the casing shrinks in the heat of the oven, it pulls up the sides of each slice, forming a little meat cupful of spicy oil.

They even agreed to a truly impractical project: developing a dough supply using only natural leavening.

Like artisanal bread bakers, who recreate premodern techniques, Mr. Falco prefers naturally fermented starters to commercial products like active dry and instant yeasts, which are effective, but formulated primarily for speed and consistency, not flavor and texture.

The starter he deployed at Upside is three years old and has been nourished by the airborne yeasts of 10 nations , gathered by Mr. Falco in his work as a consultant. He frequently travels to places like Bangkok, Kuwait and São Paulo to advise entrepreneurs on how to recreate New York-style pizza .

Because a natural starter produces dough that is both more flavorful and more unpredictable than a yeast dough, it is a far less commercial choice. But once the Upside team committed to it, Mr. Falco taught Mr. Grossman the intricacies of leavening, the role of salt and heat, and the necessity of adjusting one’s internal clock to the pizza’s life cycle.

“Dough time is not the same as human time,” Mr. Grossman said.