I think it would be a Khmer dish if it's prepare and cooked by a Khmer person. It isn't always necessary to follow someone's else recipe if you can cook the basic food already. For someone that is cooking the dish for themselves, you have the option to put whatever you enjoy eating and go wild with your own dish. You will love it because it's all the stuff you enjoy eating.
When I feel like eating a vegetarian dish, I would gather all the veggies that I felt like eating for that day and stir fry them all in the pot. Use the sauce to my liking and enjoy a dish of all my favorite vegetable in a dish make by myself.
Certain vegetable or mushroom can make a vegetarian dish pretty pricy at the restaurant and they don't give you much of the tasty vegetable. I would just get it from the supermarket and cook it myself. I will have leftover veggies for the next day to prepare myself another vegetarian dish.
Or you can always go for the all time basic mee su with no meat that the Khmer monk is having at the temple.
Noodle with veggies is an all time favorite dish.