How to prepare onions

Step 2 Cutting dice

It's all in the video.

Place the peeled onion on a chopping board, bottom down, top up.
Cut down, in a series of parallel slices, but don't cut all the way through.
This is where you'll appreciate not having sliced the bottom off.
Rotate the onion 90^o and cut in half down the middle.
If you want finer dice make a second set of parallel slices before cutting in half.

Place the halves flat side down on the board and cut from top to bottom (as the onion goes), which will be left to right or vice versa depending upon your handedness.
As you near the root of the onion you'll find it difficult to cut due to the bulb's curvature - don't struggle with it, flip the remaining onion onto it's largest side.
Discard the root base (or put it in a stock pot)

In this video you see my knife coming very close to my fingers - it's my fingernails that are closest, should I misplace the blade they'll protect me enough - sharp knife = gentle pressure (and I haven't done that for years) Again, it's good control and a good knife that makes this work.