You can make this easily whenever you feel like it. Nothing goes to waste because you can just make the amount you need Spinach with homemade sesame seasonings.
You can easily make this if you have some sesame seasoning in stock You only need a little for a pronounced flavor, so it makes a good bento dish or extra side dish.
Mix the seasoning in a little at a time, checking the taste as you go.
Enjoy Japanese food around the world.