Bibim guksu, which translates from the Korean as “mixed noodles,” is a refreshing cold noodle dish that’s a perfect meal on a hot summer day. The most common version of bibim guksu is red and fiery with kimchi and gochujang (Korean fermented chili paste), but this recipe takes a milder, more soy- and sesame-centric approach to the flavoring. (We do still use a little gochujang to add body and lots of umami to the dressing, but not enough for intense heat.) Somen is the Japanese name for the type of dried wheat noodle to use here; in Korean they are called somyeon. If somen is not available, soba, or Japanese buckwheat noodles, is a good alternative. If you wish to make it more substantial, top each serving with slivers of hard-cooked egg.