(FORTUNE Small Business) – The year was 1965, and Ruth Fertel was looking to buy a business. The 38-year-old divorcee was a New Orleans lab technician, but she couldn't send her two sons to college on her $4,800 salary, so she began scouring the classified listings. A tavern? No, she hated drunks. A gas station? Boring. Then she saw that a restaurant called the Chris Steak House was for sale. "Oh," she thought, "I'm sure I could do that!"

Fertel had never worked in food service, but her can-do drive was well established. She'd graduated from high school at 15 and earned a chemistry degree at 19. So against the advice of her banker and her attorney, she mortgaged her house for the restaurant's $18,000 pricetag, plus $4,000 more for supplies, which the banker patiently explained she'd need. They might have objected more strenuously if they'd known Chris Matulich had sold his steak house six times, repeatedly buying it back on the cheap when the latest owner failed or gave up.

Fertel didn't know she was being suckered--and probably wouldn't have cared. She was too busy learning about hostessing, waitressing, cooking, bookkeeping, and butchering 30-pound loins of beef (no mean feat for a 5-foot-2, 110-pound novice). Customers admired her pluck, and soon she was serving 35 steaks a day for $5 each, at a small profit.

Fertel's unlikely break came a few months later when Hurricane Betsy devastated New Orleans. With the electricity knocked out, her meat supply would soon spoil. But her gas broilers still worked, so she cooked free steak meals for victims and relief workers, a gesture that won her many new customers. And when Betsy's ruinous effect on area fisheries led the local Catholic diocese to suspend meatless Fridays, a traditionally slow business day became profitable. With business booming, Fertel opened another branch, a block from the original. This prompted a legal spat with Chris Matulich that led Fertel to append her first name to his, creating the famously tongue-twisting Ruth's Chris. "Frankly, I've always hated the name," she later said, "but we've managed to work around it."

By 1976 her combination of graciousness and massive slabs of premium beef had made her restaurants into Louisiana institutions. Two events then took Ruth's Chris national. Fertel designed a broiler that let her cook her prime steaks at a searing 1,800°, and she began serving them on hot buttered platters. "The butter melts and mixes with the juices from the steak. Can you imagine anything tasting better?" Fertel asked. One devoted customer from Baton Rouge couldn't; tired of driving to New Orleans for his favorite steak, he persuaded Fertel to let him become her first franchisee. Additional outlets soon followed, primarily in cities with pro football (the pigskin and pricey beefsteak demographics correlated nicely). Within a decade, 17 Ruth's Chris outlets were serving up annual sales of $22 million.

Today those numbers stand at 87 restaurants and $314 million, making Ruth's Chris the most successful upscale restaurant chain, over competition like Smith & Wollensky and Morton's. Fertel died last year, but the brand keeps growing, thanks in part to Atkins mania. Fertel, of course, never worried about diet trends. "People always say, 'I'll go on a diet on Monday.' On Sunday, they renegotiate."