The secret to a good vegetarian ramen is to add a savory, umami flavor. That can be done very simply with soy sauce, which most of us already have on hand. This will add a deep, savory flavor in an instant. The sesame oil helps with this, too! For an even more flavorful broth, consider stirring in a small amount of white miso paste or simmering dried shiitake mushrooms. Both of these will add an extra savory flavor and are delicious in a variety of vegetarian recipes!