Joyce Goldstein of San Francisco flew to Miami with six pounds of fresh phyllo on her lap.  The former owner of Square One and author of 19 books, she cooked all morning, making 300 "tastes" of bougatsa, a Greek phyllo pastry filled with cheese custard -- and sold five books.  Soon she'll fly to Baltimore to attend a conference at the invitation of the Potato Board.  She went to Copia in Napa to do "This Is Not Your Mother's Seder."