But while Mr. Phojanakong served fresh hot sauces nightly at his restaurants, he had never bottled any of them. So he and Mr. Crotty took a road trip to Geneva, N.Y, to consult with agriculture experts. A pepper specialist there said the serranos were suited to the Bronx climate, and relatively easy to grow and harvest.

Mr. Crotty described the serranos as hotter than poblanos, but milder than habaneros. Or as he put it, “They’re the Goldilocks of peppers.”

Back in the city, there were some setbacks. Mr. Phojanakong tested more than a dozen recipes before he was satisfied with one, only to have its taste and texture altered by the pasteurization process. He started over. The final recipe was created in two months, and had just five ingredients: serrano peppers, apple cider vinegar, garlic, onion and salt.

Small Axe Peppers partnered with GrowNYC, a nonprofit group currently running 50 greenmarkets across the city, to find community gardens and farmers to grow the peppers, providing them with starter plants paid for by Small Axe. The group also connected the company to marketing and distribution experts and buyers. GrowNYC gets a share of the hot-sauce profits, which it plans to use for programming.

Elly Truesdell, who holds the title “local forager” for Whole Foods in the Northeast, said that the goal of the hot sauce to support local growers made it a good fit for Whole Foods. Ms. Truesdell, a fan of serrano peppers, was also won over by the flavor. “It brings a nice balance of heat, and is different from a lot of other hot sauces we carry that rely on habaneros, and in some cases, ghost peppers, for intense spice,” she said.