Most Chinese recipes call for vegetables cut on the diagonal. Vegetables cut on the diagonal take less time cooking because more surface area is exposed to the heat source, an ideal way to cook in a wok. Vegetables cut on the diagonal also look more appetizing and can be used in almost any recipe. Here are a few tips to help you get started.
Instructions
1. Start with a sharp knife or cleaver. A knife that is dull causes you to put more pressure down and this can cause accidents. Use a sharp knife for cutting; curl your fingers under on the hand that is holding the vegetable to be cut to reduce accidents.
2. Wash the vegetables before cutting. If you wash the vegetables after cutting, they will take longer to dry and could lose some flavor. Dry the vegetables before cutting.
3. Slice the vegetables on a forty-five degree angle, sizing them according to the recipe you are making. If slicing vegetables for a stew, the diagonal cut vegetables can be cut larger because cooking time will be longer. Vegetables that are well suited for cutting on the diagonal are cylinder shaped such as carrots, bean, bok choy or celery. Round vegetables can be cut on the diagonal after you've sliced the bottom off to give you a solid base to work with.
4. Cut the vegetables by holding the tip of the knife down on your cutting surface and rock the blade up and down. This is the safest way to cut vegetables and may take some practice. Don't rush yourself and your diagonal cut vegetables will be perfect.
Source: http://www.ehow.com/how_2084112_cut-vegetables-diagonal.html