On a ragged stretch of sidewalk in northwest Harlem across the street from a dingy bodega, a weathered wooden door separates the outside world from an oenophiles’ wonderland. A homemade bar dominates the room, backed by walls plastered with cutouts from wine publications. Empty bottles of Nicolas Feuillatte, Armand de Brignac and Cristal loom like a hunter’s trophies along the shelves.

On a torpid summer evening, Branson Belchie–better known as Branson B., hip-hop’s unofficial sommelier–hovers behind the bar in search of an acceptable champagne, every move punctuated by a slight flutter of his dreadlocks. Life is too short to struggle through a bad bottle of bubbly.

“I never particularly cared for Moet, personally,” Branson offers. “Moet has a tendency to give me a headache. Back in the day, we drank Clicquot. I turned a lot of people on to Clicquot.” He lowers his voice. “At the time, Clicquot was really good.”

Branson is the man who introduced Cristal, Dom Perignon and a number of other pricey brands to his friends Christopher “Notorious B.I.G.” Wallace and Sean “Diddy” Combs in the late 1980s. Within a few years, that suggestion sprouted into hip-hop’s full-fledged obsession with champagne. Branson is widely credited with starting the craze, and his name has been mentioned in more than 60 songs over the past two decades.

A self-described street entrepreneur, Branson, 52, got involved in the entertainment business during the early 1990s, serving as road manager for R&B singer Chris Williams and DeVante Swing of Jodeci. He also did consulting work for a number of other artists, and later for the producers of the film American Gangster. As Branson’s career blossomed, so did his taste in champagne. He bought Biggie a six-liter bottle of Taittinger brut one year for the rapper’s birthday; on another occasion, he provided bottles of Cristal and Dom Perignon to singers Faith Evans and Luther Vandross.

“You bust a bottle, pour a couple glasses, and just sip on it as they engage in the creative process,” says Branson. “Sometimes people acquire a taste for one or the other. Like, ‘Yo, I really like that Cristal.’ You go back through there, they’ve got their own bottle of Cristal and they’re offering you a drink now.”

By the turn of the century Branson was beginning to realize that he’d created a trusted brand–and that it was time to capitalize. So he teamed up with Guy Charlemagne champagne to create his own label, Guy Charlemagne Selected By Branson B. In 2004 Branson traveled to France’s Champagne region to handpick the grapes for a blanc de blancs, a brut rosé and a 2000 vintage Grand Cru.

A longtime patron of Guy Charlemagne, Branson used the winemaker’s existing offerings as a template and tweaked them to his satisfaction. The process was simple enough for someone with a palate as refined as his. “If you want a little more zest to it,” he says, “you add more pinot grapes.”

Branson launched his champagnes in 2005, starting with 100 cases distributed between a handful of stores in New York. All three earned high marks from Wine Spectator, which gave the blanc de blancs a coveted 91 rating, praising its “subtle length on the finish” and its “fine balance and intensity.” Branson’s products also caught the attention of J.R. Battipaglia, store manager of Garnet Wine and Spirits on Manhattan’s Upper East Side.

“They’re really good wines, really top quality wines,” he says. “The grapes come from a village with very chalky soil. The whites tend to be very mineraly, with almost a hint of sea salt, very crisp. For the people in the champagne world who want to experience these things, it’s a unique experience.”

Battipaglia, who still carries Branson’s bubbly, says sales have slowed during the recession, but no more than other champagne labels. Meanwhile, Branson hasn’t gotten quite as much support from the hip-hop crowd as he’d expected–many artists are too busy shilling their own spirits to give him any publicity. Branson’s old friend Diddy plugs Ciroc vodka, Ludacris recently launched a cognac called Conjure, and T.I. inked an endorsement deal with Remy Martin.

Undaunted, Branson is pressing forward. Over the past few months he’s been wading through the paperwork needed to sell his wines in other states and online, hoping that a Web presence will help take sales to the next level.

“I’m just trying to solidify a market share,” he says. “I don’t want to be an overnight situation. I want to build a solid company, a solid brand, and I want people that aspire to this lifestyle to consider my product when they decide they want a glass of champagne.” His blanc de blancs ($45), brut rosé ($50) and 2000 vintage Grand Cru ($75) are relative bargains for champagnes of their quality, according to independent wine buyer and critic Lyle Fass. But Branson may need to reconsider the cost of his champagne if he wants to make a big splash in the rap world. “No hip-hopper is going to buy those wines at that price,” says Fass. “He needs to mark them up.”

A $45 sticker price may not be glamorous enough for the average rapper, but back at his champagne speakeasy in Harlem, Branson seems unconcerned. Emerging from behind the bar, he softly pops open a bottle of his 2000 vintage and tips a trickle of champagne to the floor before filling two flutes. “To life.”

“You know,” he says, taking a long sip, “I think what makes a champagne great is that you enjoy it.”