We've used this technique most commonly to chop almonds for making granola. It doesn't produce perfect pieces or slices, but it does make nicely-sized bits that work fine for most of our purposes. We can chop a cup of almonds in about 2.5 minutes with nothing other than a flat-sided knife and our hands (and something to pad the countertop). No electricity or fancy chopping devices needed.
With a little practice, this technique can significantly speed up the food chopping chores compared to using just the sharp side of the knife (we do pretty much the same thing to chop garlic cloves). Have you come up with a simple and fast method to chop your food? Tell us about it in the comments section below!
*DISCLAIMER: Talk to an expert practitioner before you start iron palm training. There are many risks and important details associated with the training itself that you need to know about before you begin.