THE simple hamburger isn’t so simple any more.

Over the last decade or so, there has hardly been a serious chef in America who hasn’t taken a shot at reinventing or improving it. They have trained their skills on every element, from the precise grind of beef to the ketchup and pickles. Some have turned their bakers loose on reformulating the bun.

By most accounts, the burger’s upward journey began eight years ago, when Daniel Boulud stuffed ground sirloin with truffles, braised short ribs and foie gras at his DB Bistro Moderne in Manhattan. A few weeks ago, Mr. Boulud brought things full circle, opening a burger bar on the Bowery called DBGB Kitchen and Bar.

While some chefs have groused quietly about the insatiable demand for burgers, most are philosophical. “All chefs can be frustrated by the buying public sometimes,” said Clark Frasier, a chef with restaurants in Massachusetts and Maine. “In this economy I’m happy to sell anything they want to eat.”

All this high-powered attention has produced some new ways of thinking about and cooking burgers. Interviews with 30 chefs provided dozens of lessons for the home cook that aren’t terribly difficult and don’t cost much money. And it all yielded the ideal burger.