Vegetable selection and the way they are cut play an important part in stir fry.  To me, a great stir fry is one that is full of color AND mouth feel.  As a result, correctly selecting and cutting vegetables for stir fry is important.

I prefer healthier stir fries so the ratio of meat to vegetables is 1 to 2 or more.  I also select a range of colors and the variety contributes to a nutrient dense dish.

Tips on selecting and cutting vegetables for stir fry

Color.

I believe that color is important.  Having a variety of vegetables makes for a more appealing (as well as healthy) dish.  It is also important not to overcook your vegetables which result in  dull, limp vegetables. 

Crunch.

Besides looking appetizing, I also believe that different textures in your stir fry is important. Having a variety of textures makes the mouth feel and dish more interesting. I always try to add an ingredient or two that gives the dish a little bit of crunch. Crunch gives punch!

Ingredient size.

Since Chinese people traditionally eat with chopsticks, there are no knives on the table to cut up large pieces of meat.  Every piece in your bowl needs to be bite-size and able to be picked up with chopsticks.  Therefore, when prepping and cutting your ingredients, make them bite sized or at least cut them to a size that won't require needing a knife.  The smaller pieces also makes it easier to cook and toss during a stir-fry.

Consistent cuts.

Consistent cuts = consistent cooking.  This means that a group of ingredients need to be relatively uniform in size in order to avoid over and under cooking. The sizes of the different groups can change. For example, keep all you green leafy vegetables the same size and all your carrots the same size.  Also, for aesthetic reasons, if your meat is diced, consider dicing the vegetables and if the meat is sliced or in strips, do the same for the vegetables.

Prepping your vegetables for stir fry

Lay out your cut vegetables in order of cook time, from thick stemmed vegetables which take longer to cook to those that don't require too much cooking.  When stir frying, this will allow you to place the ingredients into the wok in a certain order to prevent overcooking the vegetables.