Get your knife razor sharp first. This is an absolute must! If you get lots of tears when you cut onion then your knife is too dull; sharpen it. Peel the onion and cut it in half. Cut it into slices across the wide side about 1/4 inch thick without cutting through the stem. Next slice downward cutting the onion into sticks again without going through the stem. Next cut across the top cutting it into a dice and toss the remainder of the stem. Scatter the pieces on a paper towel and cover with a second paper towel. Pat dry as well as possible. Transfer to the cookie sheet and place in the lowest part of your freezer for about fifteen minutes. Bag them in Zip locks as quickly as you can possible move and return them to the freezer. Question, why freeze?? Deylhdrated and reconstituted are just as good and I like the transportability of the dehydrated as well as using the dry flakes in gravy recipes!