kalguksu noodles
Flat, fresh wheat noodles made from flour, water and salt, traditionally cut by knife from rolled-out dough. Soft with a gentle chew.
Kalguksu noodles are Korean wheat noodles whose name means "knife noodles": a dough of flour, water and salt is rolled out, folded and cut into flat, often slightly uneven strips. They taste plainly of wheat and are soft, with a light chew that is never rubbery. What matters most in cooking is the starch on their surface, which leaches into the broth as they cook and thickens it slightly, which is why they are usually cooked directly in the soup. Fresh or frozen kalguksu noodles can be found in well-stocked Asian grocery stores in the chilled or frozen section, dried ones on the shelf or by mail order. Because the dough is so simple, they are also often cut by hand at home.
Substitute:
The closest substitute is homemade noodles of wheat flour, water and salt, rolled thin and cut into strips about five millimetres wide. Fresh flat Chinese wheat noodles or thin udon also work, though udon are thicker and firmer. Italian ribbon pasta made from durum wheat or with egg is firmer, releases less starch and barely thickens the broth.