Free food. Hard for a debt-ridden urbanite to resist. Especially when it's hearty, home-style fare like salsa chicken and Southern potato salad. But the complimentary meal (6 p.m. till it runs out) isn't the only reason to swing by this venerable Brooklyn joint. A retro backdrop of chrome-piped diner chairs, Escher-esque flooring, and tinsel-fringed beams is invigorated (tastefully, somehow) by a dose of funk shui: Porcelain dogs peek out the windows; a flapper-styled mannequin stares into space; the old piano's embedded in the corner. You get intimations of Cellars' heyday as the local hangout, packed to capacity, pumping jazz and r&b for regulars and kings. In '78, Ali stopped by to promote his short-lived candy bar; Lou Rawls and Bill Withers visited. It's a quiet place now, mostly, eminently comfortable and classic. Mr. Cellars does all the cooking himself, shakes an expert cosmopolitan ($7), and makes a Long Island tea ($8)vodka, gin, light and dark rum, tequila, and Cointreau (the good stuff)that gets the blood flowing. Sweet-toothed tipplers should try his original "Reese's" Peanut Butter Cup (Irish crème, Frangelico, Godiva; $8); the rest of us drink bottled beer for four or five dollars. So why/how does Mr. Cellars give away all that food? "It's my way of saying thanks to all the people that have come here over the years," he says. Long live the neighborhood (bar).