Japanese Udon noodles can be round, square or flat with a texture suitable for more hearty dishes. They are made from wheat flour, salt and water. Although Udon noodles can be served cold, these thicker, soft, but slightly chewy, white noodles are usually served hot with various toppings, added to a hotpot dish and cooked with other ingredients, or sometimes included in a curry soup. Udon can replace soba in traditional soba recipes and some dishes even mix soba and udon noodles to give a variety of textures.