If there is one reason to welcome fall, it's that maybe then we can score another braised lamb shank at Yorkville Café. Slowly simmered in a pinot-noir reduction sauce, smothered in a layer of well-seasoned vegetables, then settled on a cushy bed of basmati rice pilaf, this lamb shank is one of the few really good things that happened to us last winter. Then again, there was Yorkville's platter of succulent deep-fried oysters . . . the aromatic pan-roasted chicken . . . the thick grilled pork T-bone chop with cranberry-rosemary demi-glace . . . Maybe cool weather won't be so bad, after all!