Being married to a chef has many perks. One of which is learning proper knife cutting techniques. I had no idea I could dice an onion so quickly, easily, and precisely.
First, cut one end of the onion, and then slice in two from the top.
Peel, and then slice as pictured above.
Slice from the other end once or twice, depending on the size of the onion.
Then slice again, the opposite direction.