Do as the locals do and escape the heat by taking the metro out to the city's most dazzling shopping mall where a 5th-floor food court is waiting to wow you with flavours from across China – Shanghai dumplings, Chongqing noodles, Hong Kong roast duck... Dishes are clearly priced and displayed, so are easy to order.
Top-up a purchasing card (refundable deposit ¥10) with as much as you think you'll need, then hand it over as you order. You'll get any outstanding balance back when you return the card.