Learning how to brunoise can be a very painstaking and difficult process that takes a lot of practice to perfect. Brunoise is a chopping technique in which you dice food into very small cubes measuring around 1mm to 2mm and is an important part of French cooking. The resulting brunoise can be used as a garnish for many dishes or to flavor soups or other foods. The ideal brunoise should produce cubes that are uniform in size as much as possible, but most chefs admit that this is an ideal that is difficult to reach.
Here is a brief overview of how to brunoise. First, shape the vegetable you will brunoise into a rectangular or square shape by cutting its four sides. Then, julienne the food by chopping it into thin lengthwise slices. Stack the slices and then hold them together lengthwise. Then, chop the slices into fine cubes. Hold the food with your fingers in a claw-like position with the tips pulled back and the knuckles facing the knife, which will help prevent injury while still allowing you to hold firmly to the food being cut.
Cutting Bits
Here is how to brunoise an onion. First cut an onion in half and place one half on the cutting board flat side down. Then start cutting the onion into thin slices. Once you've done that, turn the onion sideways and then make two slices parallel to the flat edge, being careful not to cut all the way to the end, leaving a bit to help keep the onion together. Then start chopping the onion to make brunoise. If there is still enough at the uncut end of the onion to brunoise, repeat the process. Then look through the crumbled sections and further chop any that are too big.
To brunoise shallots, which belong to the same family as onions, a similar process is used. You prepare the shallot in the same way as the onion, by peeling it and then trimming the root. Instead of creating julienne, however, you simply make parallel cuts that are close together across the surface of the shallot, but ending just before the root. Then chop the shallot in a sawing motion. When you're holding the chef's knife, place your ring and pinky fingers on the handle and pinch the blade between your thumb and index finger. Your middle finger should be on the bolster (the junction between the blade and the handle) of the knife. This will allow you to have more control over the blade and give your cuts more accuracy.