You don’t really need a recipe for stir-fries, though sustainablemum has provided a good framework! In general you just want to:
1) make sure you do the whole thing on REALLY high heat, as high as your cooker will allow, in a wok if possible, working quickly (so get everything ready, chopped, etc. before you turn on the stove);
2) make sure your wok or pan is large enough so that your ingredients are not crowded in, or they will steam instead of stir frying—you don’t want the veggies releasing a lot of water;
3) use an oil suitable for very high heat (we use peanut or sunflower oil; never, ever use olive oil for stir fries!) and heat it almost to smoking point before adding in the first ingredients;
4) start with a combination of finely minced garlic, ginger, shallots, spring onions (just the white part; use the green as garnish at the end) or any combination of these (I sometimes just use one) and fry this until it turns golden but not brown;
5) put the veggies and meat in in the order in which they cook and leave the veggies slightly undercooked at the end; it will continue to cook in the heat of the wok for a bit (in your case, I’d put in the mushrooms first, then the courgettes after a few minutes as oyster mushrooms are quite delightful slightly charred in a stir fry, I’ve found);
6) keep seasonings as simple as possible and not too many: you can either use a premade stir-fry mix or just soy sauce or soy sauce+oyster sauce+toasted sesame oil (a favourite combination here) or oyster sauce+a bit of chili paste if you like heat;
7) mix the seasonings separately in a little bowl and stir them in at the end, after you turn the heat off, if you don’t want the green veggies discoloured;
8) finally, this is just me and I’m sure many here will disagree, but I am a purist and believe that stir-fries should always be served with white rice, never brown .
Hope this helps!