Ponzu

By simply adding citrus juice to soy sauce, you can make a quick homemade ponzu although additional ingredients such as mirin, sake, katsuobushi, kombu would help to add depth and a good umami flavor to it.  You can also buy ready-made ponzu at a well stocked supermarket in the US, but a homemade can be a lot tastier.   So if you have a time, I would recommend you to make one at home.  It will keep for about a month in the refrigerator.

I describe a versatile Ponzu sauce good for a general use here, but you can play with the amount of soy sauce or citrus juice depending on the meal you are planning.  For example, if you are eating sashimi with it, you might want to increase the amount of soy sauce.  There is no right proportions for it; so, be experimental.  Dried bonito flakes and kombu are important ingredients for me to give depth to the sauce, but you can omit it if you don’t need it.

It would be great if you can get Japanese citrus juice, but if not you can simply use other citrus fruits available here such as a lemon, a lime, or a grapefruit.  I recommend to mix at least two different kinds of fruits so the flavor gets a little bit more complex.  I like to use a lemon or a lime as a main base, and add sweeter juices such as grapefruit or orange as a secondary juice.  Alternatively you can get a small bottle of yuzu juice at a Japanese grocery store or a specialized gourmet market that you can use to make ponzu.