Wash the coriander and cut width-wise into short sections. Mince the ginger, spring onion, and garlic.
Clean the potatoes, cut into matchstick-sized strips, and soak in cold water to remove excess starch (it also prevents the potatoes turning black). Drain the potato strips before cooking.
Combine the salt, ground pepper, vinegar, sesame oil then add the minced ginger, spring onion, garlic and coriander in a bowl and mix well.
Heat a wok to very hot and pour in the oil. Add the potato strips and quickly stir-fry for 1-2 minutes. Add the sauce mixture and stir-fry for 1 minute until the sauce coats the strips. Remove from the wok and serve.