A year or two ago the chef at Imperial Wok on North Broadway, North White Plains, left for greener pastures elsewhere. The quality plummeted, and the place seemed destined for mediocrity. Three weeks ago a new chef arrived, supposedly directly from Szechuan, and he's got the goods! Two recent visits have gone very, very well. Spicy braised whole fish, shredded beef with basil, Taiwanese chicken casserole, shrimp with hot chile paste and Chinese cucumber and more have been back to their usual, delicious standards. I haven't yet tried their (former) standout dish, Fish Fillet in Pickled Cabbage Soup. N.B.: The chef's day off is Wednesday.