This derives from a recent trend in Japan of dumping canned ready-made green curry onto sômen noodles. My green curry somen deviates from the original by mixing in some fish broth and kaeshi (mixture of mirin, sugar, soy sauce) into the green curry to temper the heat and to increase the amount of the very little green curry that I had left. However, if you have enough green curry, you can also just dump it on the boiled sômen noodles.
Strange as it seems, it’s a pretty marvelous combination. The fish broth and kaeshi actually works well with the fish sauce that’s already present in the curry.