Roasted sesame seeds are a popular topping for ramen. The roasted sesame gives the dish a nutty note and gives it an additional texture. You can simply roast the sesame in a pan without oil or buy already roasted sesame from an Asian store or supermarket. You can sprinkle the sesame seeds over the ramen soup before serving. Alternatively, you can crush the sesame seeds in a mortar to make them finer and then sprinkle them on the soup.
The Japanese word for sesame is "goma"