Cut and trim the Stem and Root of the onion. Make sure you leave the root end intact as it keeps the it held together. Holding onion, cut both ends.
Place the onion stem down on the cutting board. This will stabilize the onion so that you are able to start slicing.
Then cut the onion in half. Slice the onion all the way through the root in.
Peel the skin back off the onion. Peel the papery layers and the top layers from one half of the onion.
Begin cutting the Onion. Place half of the onion on the flat side. Use angle cuts to begin cutting the onion going to the root of the onion.
Slice the Size of Onion. Space your cuts depending on the size of onion that you want.
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Notes
Once you have peeled and cut in half lay the flat size of the onion on the cutting board. Begin chopping in one direction - Horizontal cut of the onion in whatever size that you want.They can either be thin slices or thick slices. Then chop in the other direction - Twist your cutting board and turn your onion, and begin chopping the onion slices into a chopped size of onion.