Successful stir-frying is quick because all the slow work happens first. Vegetables are cut evenly, sauce is mixed and noodles or rice are ready before the wok is heated.
Use high heat, but cook in small batches. An overcrowded wok loses temperature and turns a stir-fry into a watery stew. Return everything only when the sauce is ready to coat it.
The final minute matters most: toss continuously, watch for a glossy sauce and serve immediately while vegetables are still bright and crisp.