Lately, she said, that while free of favism, she worried that she suffered from some other mysterious allergy that led her to “sneeze four, five, six times.”

“Who knows?” her husband interrupted.

“I’m talking,” she said. “Maybe it’s the husband.”

A few yards away, Sara Lauteri, 29, a fava vendor, stood behind heaping piles of pods, advertising how they were “super fresh, picked this morning.” She stuffed them into brown bags for customers and said no favism sufferer had ever been reckless enough to approach her.

“Their red globules practically explode,” she said.

Paola Romani, 59, nodded in agreement.

“It’s a nasty disease — it takes you by the throat,” she said. Then she opened a pod, popped some beans into her mouth and bought a bag to go with her brick of pecorino. “May,” she said with a shrug, “is fava.”

Gaia Pianigiani contributed reporting.