Diwali cleaning DIY: How to remove stubborn stains from steel utensils

Every Diwali, the steel utensils come out from the back of the cupboard: the big kadai for sweets, the tall vessels for festive cooking, the plates and katoris for guests. And every year, the same thing happens. Some have burnt bottoms from last year's halwa, some are covered in cloudy white spots, and a few have that odd rainbow tint nobody can quite explain. Steel doesn't rust easily, but it doe