It's not easy to find this out-of-the-way little mercado and café on the city's West Side and there are loyal fans who don't want you to find it. You see, it's not terribly big, and it has become the secret "in" place for hipsters in the art and culinary communities, who like to hog the tables and booths on Sunday mornings, when the delicious huevosrancheros are a curative to a late night of partying. Well-traveled gourmands swear that the fare at Ortega's is the real thing. It's also a see-and-be-seen place on weekend mornings (it starts serving at 7 a.m.), which is why one legendary local party girl rolls out of bed, pops a Tylenol, then slips on her Manolo Blahniks at an ungodly early hour for Ortega's coffee, chips and guacamole. "If you want to know what cool people are doing downtown," she says, "that's where they hang out."