Check your oil spray, because that's likely where the pasty spots came from, not the flour. Most cooking sprays have lecithin and other stuff in them that gunks up when it hits a hot surface, and on frozen food it can pool in the little cracks and turn into exactly the weird clumps you're describing. Straight oil in a pump bottle or brushed on thin works way better than the aerosol cans for that reason. @rodriguez.cora you're right that flour on frozen food steams, but that's only if you put too much on, a thin dusting and a shake in a bag keeps it light enough to crisp without going gluey. Also patting them dry first does nothing for frozen sticks since they're already rock hard, the ice is the whole problem, so a dry surface isn't happening either way. The real trick is not crowding the pan or basket so the steam can escape instead of sitting there and steaming the coating.