Lay pappadum wafers (5 in.) slightly apart on a baking sheet. Broil 4 to 6 inches from heat until wafers begin to buckle, 15 to 25 seconds; watch closely - they scorch easily. Turn wafers over and broil until surface is blistered, 8 to 12 seconds. Transfer toasted wafers to a rack. Repeat to prepare at least 2 wafers per serving. When cool, store airtight up to 1 week.