You need an Onion, Knife and Cutting Board
Trim ends of onion.
Slice in half.
Peel off jackets put in compost or feed to your pig. Our pig loved onion!🐷
Make several slices 3/4 the way though onion.
See the cuts? Only 3/4 the way.
Turn onion and slice the other way, starting with the side that was cut.
Slice till get to the part that was not pre-sliced
Lay that part in its side and slice again.
You're left with Diced Onion!