Visitors to this season’s Harvard Farmers’ Market will see several new vendors, among them Taza Chocolates from Somerville, a company that advertises as “the only maker of 100 percent stone-ground chocolate in the United States.”

“We set out to make chocolate in a very traditional, low-tech way, the way we saw it being made in Oaxaca,” said Taza co-founder Larry Slotnick in a recent phone interview. “In the southern region of Mexico, chocolate is not considered candy or a child’s treat, but, like coffee, part of the daily routine.”

Taza sells organic chocolate in traditional bars, round disks of Mexican chocolate made without cocoa butter, chocolate covered cocoa bean bits called nibs, and shaved chocolate. They also sell raw beans.

According to its website, www.tazachocolate.com, Taza not only produces good chocolate, they are also good guys who adhere to the slow foods ethic that we should eat food that tastes good, is produced in an environmentally responsible way, and that fairly compensates producers for their work. True, or modern marketing hype?

As Slotnick talked, skepticism gave way to thinking that Taza is the real thing.

“Chocolate is food, grown by farmers like other produce. Farmers usually get a raw deal when you see where money goes in the food chain,” said Slotnick, who talked about the difficulties building a premium-brand business in keeping with their commitment to sustainable practices.

For them this means being involved in the process from “bean to bar.” Taza buys most of its chocolate at above fair-trade prices from a cooperative of 800 family farms in the Dominican Republic. They pay farmers above fair-trade prices for organically grown beans and personally visit farms to confirm that field workers are fairly treated. Their commitment to sustainable practices in building such a business also means trying to build a business without outside investors or a national distributor, paying their Somerville employees a reasonable wage with benefits, and maintaining a low carbon footprint.

All of Taza’s employees walk or bike to work. Slotnick and other Taza employees transport products and equipment to eight Boston area farmers’ markets using cargo tricycles from Mexico or bicycle and a cargo trailer.

Initially, Slotnick, a co-founder of the Zipcar and a committed cyclist, was hesitant to come to the Harvard market because of Taza’s low carbon commitment. However, he decided to bicycle his wares each Saturday from his Arlington home to Harvard, weather permitting.

It all means a lot of sweat equity. Slotnick and co-founder Larry Whitmore are into their second year of high passion and low pay, efforts they hope will lead to a sustainable business with a loyal customer base without compromising their initial values—or their chocolate.

The Harvard Farmers’ Market will be open from 9 a.m. to noon each Saturday from Aug. 23 through Oct. 25.