If you stroll in for a late lunch after the noontime crowd has thinned, the staff may be sitting around enjoying their own communal midday meal, but they will be in relaxed, even bantering mode, with more time perhaps to help you navigate the non-English menus. For it is in those unadorned photocopied sheets, slipped under the glass of the pink-cloth tabletops, that the treasures of this simple Chinese restaurant lie. Ask for the house-made, hand-cut "knife noodles" -- a specialty of China's Shanxi province. Explaining why this regional specialty of interior north China shows up in a Shanghai restaurant, the waiter shrugs and says, "The chef is from Shanxi." Try any of more than a dozen knife noodles offered, most at $5.50 each. Just be sure to order No. 8: chunks of slow-simmered beef with bright green spinach in a big bowl of rich, chile-spiked broth. Bite slowly into the dense, chewy noodles. Savor a bit of heavenly peace.