These wheat-based Japanese noodles are available both dried (used in this recipe) and fresh. Dried udon are flatter than their fresh counterparts and closer in texture to linguine.
Depending on what you like and what's available, this recipe works well with both red (which has traditional curry ingredients plus chile powder and can be spicier) or classic Indian yellow curry powder.
Curry noodles are a favorite food. I know everything is my favorite food, but Thai street food, especially the kind sold off a boat floating dock side, has to be really good food.