By THÉRÈSE MARGOLIS Ah, brunch! That wonderful, leisurely, a-little-too-late-for-breakfast-but-not-late-enough-for-lunchtime, ideal-for-weekends, perfect-for-lingering-over morning repast that sends cautious calorie-counting and clock-watching to the wind and lets you savor a wholesome meal with friends and family without rushing off to work or breaking the bank. Indeed, a brunch can transform a simple poached egg into a gourmet luxury with a dab of hollandaise