Absolutely! Chop Suey is a stir fry and lends itself to being a great vegetarian meal. Simply omit the chicken, add in more veggies and make a few changes to the sauce. To bulk up the dish, I would add several different vegetables. Baby corn, bell pepper, and even a second type of cabbage like bok choy are all great choices. The stalks of the bok choy add a wonderful crunch and are often used in Chinese cooking. You can replace the soy sauce with liquid aminos and use a mushroom soy sauce in place of the oyster sauce. Here is a recipe I found for vegetarian oyster sauce, if you wanted to give that a try. Replace the chicken stock used to make a cornstarch slurry with a vegetable stock or water.