The alkaline solution called kansui is what gives ramen noodles their characteristic chewiness. Kansui is difficult to find, so we give a substitute—baking soda that is baked in the oven to increase its alkalinity—here. Be sure to prepare this ahead. Also, if you’d like to give the noodles the traditional deep yellow color, add a pinch of riboflavin. (This originates from a time when noodle makers used this to mask the darker hue of less-refined flour.) Ramen is a much drier dough than egg pasta. At first, the dough will be craggy and messy. Don’t give up! As the mixture is worked and run through the pasta machine, it will gradually come together, forming a silky, beautiful dough.