Use a mandolin to directly slice the cucumber into a deli quart container. Alternatively, use a knife to thinly slice a cucumber and place it in a bowl.
Add the soy sauce, toasted sesame oil, fish sauce, sugar, MSG, garlic, green onions, and toasted sesame seeds to the container (or bowl).
Place the lid on the container and shake until the cucumber slices are coated evenly with all the ingredients. If your cucumbers are in a bowl, toss well.
Enjoy immediately, or place in the fridge and marinate for a couple of hours then enjoy. The cucumbers will be crunchier the faster you eat the salad, so if you want a fresh cucumber salad, enjoy immediately. If you want more of a quick pickled cucumber salad, let marinate for 1-2 hours before enjoying.