Honestly there’s not a whole lot you can’t put into a stir fry just keep an eye on the cooking times, you don’t want to be dropping large pieces of gourd with your bok choy for example, and focus on what’s fresh at the market. A lot of times my menu changes (or more often is created) based on what I find fresh and in season or bargain priced.
Just for some ideas and staying away from meat… garlic, ginger, thai eggplant, all sorts of mushroom varieties (shiitake, oyster, straw, enoki, cremini, wood ear, etc), snake beans, chinese chives, water chestnuts, sweet potato, plums, asian pears, bok choy, watermelon rind, lychee, pea leaves, egg, daikon, green onion, pickled anything, vermicelli, dangmyeon, napa, carrot, spinach, tofu, cactus, chinese eggplant, any chili pepper you can handle, choy sum, lotus root, spaghetti squash, chrysanthemum leaves, snow peas, chinese broccoli, taro root, the list goes on…
A simple one I do a lot is:
Garlic, onion, ginger (which can be used as a base for just about any stir fry) with shiitaki (or oyster when I can get them nice and fresh), water chestnuts, snow peas, and dangmyeon. Season it with dark chinese soy sauce, a little sugar, regular soy sauce, and white pepper. Serve it topped with green onion, some chopped fresh chilies, a little thai basil, and a drop of sesame oil.