Are you sick of key lime pies that taste treacly, like green-color candy? Yet you live in South Florida and, damn it, when visitors come to call, they expect the local confection. Fret not, there is hope. Oddly enough it comes from sternly dressed German Baptists. More than a half century old, the Knaus Berry Farm in Homestead is rightly celebrated for its pecan rolls and fresh strawberries. On weekends between the middle of November and the last Saturday of April, customers brave long lines to buy fresh pastries and milkshakes from these traditionalists, whose long beards and conservative clothes often cause people to mistake them for Amish. The key to their key lime pie, they say, is the topping. These Baptists use cream cheese in place of whipped cream. They also exercise a puritanical control over the sugar in the lime filling. The result is a sublime and sophisticated interplay of tartness and sweetness, truly a proper dessert with coffee after dinner. At $6.50 for a small pie that serves about five, this treat is moderately priced. Those who arrive at the farm late in the day are unlikely to find any left.