Like your average American male, I quest after long life -- with benefits. Which led me to investigate the food habits of nonagenarian Cuban musician Compay Segundo.

He was already 90 when I interviewed him in 1998 at a South Beach hotel. (He died in 2003.) The old guy had found full-blown fame the year before with Ry Cooder's Buena Vista Social Club -- his infectious song Chan Chan was the biggest hit on the CD. When I caught his act at a record-industry showcase, Segundo not only sang with feeling, but he soloed on guitar with all the verve of a metal rocker.

As for his verve in other areas, he told reporters he was thinking of getting married again and having another child. And a young female record exec told me he came on to her, boasting, ``I can still give a woman a good time.''

A lifestyle to inspire one's golden years, which were already inching up on me.

As I waited for my turn to interview him, I noticed two things. One, he smoked big Cuban cigars. Two, he lunched on a plate of black beans and rice -- nothing else.

Being only an occasional smoker, I discarded the notion of puffing on Havanas for the sake of libidinous longevity. But black beans? I could do that.

Compay Segundo's sexy-old-man diet made sense. Black beans are a great source of protein, fiber and antioxidants as well as vitamins and minerals. Nutritionally, they are superior to most beans.

As for my hero having his beans and rice unaccompanied, that made sense too. As any health enthusiast will tell you, beans and rice make a complete protein; eating them as sides to a heavy meat dish and another side of starch, like yuca, is not only redundant but fattening.

There are many frijoles negros recipes, some in books, many handed down in families. A favorite one, from Nitza Villapol's classic Cocina al minuto, calls for soaking the beans overnight with a green bell pepper. Most recipes demand some sugar -- the Cuban sweet tooth at work. Then there are spices and herbs: Cumin, oregano, bay leaf, cilantro, culantro, mildly hot chile. Opinions are divided on which, if any, should be added.

A popular version is named after a prominent Cuban family, Valdés Fauly; according to published recipes, it includes pimiento. And though it's probably a flourish added by Spanish immigrants, black beans are often finished with a dash of wine or vinegar and a dousing of olive oil.

Finally, there's punto, the point at which the bean broth thickens and the flavors ripen -- a common ploy is to dormir (''sleep'') the beans, letting the cooked dish sit overnight. Recipes often call for taking out a ladleful of beans, mashing them, and adding them back to the pot to thicken the beans. But purists insist they will cuajar -- literally ''curdle'', i.e., thicken -- on their own if you cooked them right.

But what's right? Ah, experienced cooks will tell you punto is something you reach through talent and experience, and once you have punto, you can't miss, like a blindfolded Zen archer always hitting the target.

In Mexican cuisine, black beans are used to make that silky side dish, frijoles refritos. And in Brazil, black beans are the staple of feijoada, a weekend lunch dish laden with reconstituted dried beef (tasajo to Cubans), sausages, cured pig parts (jowls, ears, tail, you name it) that is guaranteed to knock you out -- particularly if prefaced by a couple of caipirinhas.

By contrast, Cuban frijoles negros is totally vegan, although some old-time recipes, seldom cooked any more, call for tasajo.

Traditional Cuban households will make beans every day for lunch. Black beans top the list, but red kidney beans are also a favorite, as well as split peas, lentils, garbanzos, navy beans. Unfortunately, cooking beans takes long hours, and these days there is seldom a housewife or househusband around to watch the beans, so quemar los frijoles (burning the beans) is a great danger.

My Cuban household is one of those where no one has time to cook beans, so I eat them out. This is also true of stockbroker Tony Rodríguez, a local aficionado who takes his black beans as seriously as his wine collection. Rodríguez, who is in his 60s, is trim (he works out) and elegant (he wears tailored suits), belying the notion that eating frijoles negros will make you fat.

''Of course,'' he says, ``I nearly always eat nothing but grilled fish and steamed vegetables, besides the beans and rice.''

Rodríguez faxed me a list of his favorite black-beans eateries (see sidebar), adding that the ones at the Pollo Tropical chain were good, too. I did a little research of my own and hit the jackpot at one of the oldest restaurants in Little Havana, El Pub on Calle Ocho.

Wanting a pure experience, I ordered a bowl of black beans, no rice. The flavor was deep, which is what one wants, with rich overtones and undertones I may have missed if I'd had it as a side with the usual roast pork, white rice and yuca in garlic sauce. Needless to say, it would take me a year or two to sample every plate of frijoles negros in town, but as far as I'm concerned, El Pub rules.

I remembered, as I had my potaje de frijoles negros, that black bean soup -- in a very different recipe -- is an old American classic, gone the way of turtle soup as a first course at fine restaurants. And that it was traditionally served with a glass of dry sherry, which the diner could either pour on the beans or sip with the soup. Wine and black beans -- Tony Rodríguez's favorites -- were made for each other.

Cubans do eat black bean soup as a first course, usually in a smooth purée. The trick is to make enough frijoles negros to serve the first day with rice, then puree the leftovers and heat them the next day for a purée de frijoles negros.

Finally, black beans are cooked with white rice into the mélange known as moros y cristianos, Cuba's version of the peas-and-rice side dish that is eaten on every Caribbean island. However, Brazilians, always ahead in sophistication, serve the best side dish: white rice bathed in the strained broth of a feijoada. Elegant.

As to whether frijoles negros help a man live as long and randy a life as Compay Segundo's, I don't know.

Yet.