Sommelier Daniel Johnnes – New York’s premier wine guy about town – signed on as wine director at Daniel (Boulud, that is) in the fall. And his boldest move took place on last Tuesday: a seven-course black truffle-themed dinner at which guests were invited to bring their own wine. That’s right: a BYOB dinner. Specifically, “Rhone wines 1990 and older.”

Bring your own bottle to Daniel, a haute cuisine epicenter boasting a treasure-filled, award-winning, 1,500-label wine list? Normally, that would be out of the question. “We don’t accept that clients bring their own wine to the restaurant,” Daniel Boulud told me flatly. Not even for a hefty corkage fee. Until last Tuesday night, that is.

But what a night it was for the nearly 50 wine buffs, many of them collectors of the rarest and best. They didn’t all know each other, but they did all seem to know Mr. Johnnes. For 20 years, the Manhattan native, 50, was wine director at Montrachet, where his Monday-night BYOB dinners were convivial affairs at which bottles were exchanged freely between tables of perfect strangers. “I wanted to bring a little of that less formal, more accessible spirit to people who are really passionate about wine here at Daniel,” Mr. Johnnes said.

He also brings a version of the Burgundian bacchanale called “La Paulee” to New York every other year. Persuading Mr. Boulud to accept the BYOB concept in a restaurant with a cellar well-stocked with great Rhone wine wasn’t easy: “I won’t say it was a risk for him, but more like an adventure,” Mr. Johnnes said.

And so the diners arrived, checking their coats but not their bags containing precious cargo. Mr. Johnnes, a dark-suited, compact man with a halfback’s quick movements, flanked by two assistant sommeliers, grouped the wines on a long counter according to table assignments. With eight diners to each table, an array of wines was assured. As everyone took their seats, in fact, almost 100 bottles were ready to be uncorked.

“You’ll notice this is Tuesday,” Mr. Johnnes said, welcoming the guests. “Monday night is for Montrachet.” Contrary to the usual exacting standard in Daniel’s public dining room, he warned, “We are not here to give you perfect wine service.” No matter how many wines were sipped, each guest would get “only four wine glasses.”

With the first course (Tuna a la Plancha with celery, black truffles, and mache nantaise), the table next to mine was enjoying a magnum of ultra-rare white Hermitage 1989, from the esteemed grower Chave. I wished that bottle had been at my table, but not for long. Mr. Johnnes soon came over to pour the remaining half of the magnum in our glasses, with the compliments of its donor. Rhone white wines can be high in alcohol and low in freshness, coming in a poor second to their red counterparts. But not this one. It sent up a surging aroma of petrol, somehow more appetizing in this wine than at a gas pump. In the mouth, it was a wedge of peach and ginger essences.

Not that my table was lacking for Rhone treasures. A young woman opposite me contributed a quartet of Hermitage “La Chapelle” reds from Paul Jaboulet. The youngest of them, from 1984, tasted like it could have been the oldest: soft, sweetly ripe, and velvety. And the oldest, from 1969, might easily have been the youngest. It was a syrah potentate, youthfully brilliant in color and abrim with raspberry fruit. In between those two wines, the 1983 La Chapelle was funky and redolent of saddle leather, and the 1978, considered a classic, silky and beguiling. One doesn’t hear talk about wine prices at the table, but I did hear it whispered at my table that the replacement cost of a wellstored bottle of the 1978 “La Chapelle” is about $1,000.

Mr. Johnnes concluded his pre-dinner remarks with this admonition: “When you no longer know which wine is in your glass, it’s time for a cup of coffee.” For me, that time arrived with the fifth course, Tournados Rossini with a trufflelaced sauce perigueux – or rather, with the superlative pair of wines that went with it: Guigal’s Cote Rotie, “La Landonne,” vintages 1995 and 1982. The younger of these two wines evoked ripest blackberries with a licorice edge, while the older wine, still brilliantly purple after almost a quarter century, resonated with dark berry and grilled meat flavor. It’s a good thing these were stupendous wines, because what I drank with the cheese course is lost to memory. I sipped my coffee with a meringue laced with black truffles.

When I asked Mr. Johnnes, a few days later, how he felt about the dinner, he said: “The heart of the matter is that this kind of event, which is kind of my signature, was a way to interact with people, share with old friends, make new ones. And as special wine dinners go, it was affordable.” Indeed. The cost of such evenings, when Daniel supplies the wines, can jump to four figures.

And how did Mr. Boulud feel about Daniel’s first BYOB dinner? “I was very pleased,” he said, “especially to see many faces I didn’t know. “Will it happen again? “We could do it once a season,” he answered. “We could give each dinner a theme. Maybe the next wine with be Burgundy. That’s the night I want to be the sommelier, not the chef.”