By Lenn Thompson, Executive Editor "I'm not ready to give up riesling to our friends up north." That's how Jim Silver, general manager at Peconic Bay Winery, kicked off a recent vertical tasting of ten Peconic Bay Rieslings for a group of 30 or so wine club members and a few press folks. By "friends up north" Silver was, of course, referring to wineries in the Finger Lakes, where this country's best rieslings are born. Vineyard-wise, the Finger Lakes are still dominated by hybrids, and even natives like Concord, but most of the best wines there are made with riesling.…