Pour vinegar, salt, pepper and sugar into blender, blend. Tear the herbs and add to the blender, blend. Add green onions and fresh spinach, blend. The spinach helps make the color darker and thickens the sauce
Add oil slowly with the motor running, puree until smooth. If you want to make the sauce thicker, add additional herbs. Store in a tightly sealed container, should keep for up to three days.
For best results use Shiso Sauce the day you make it.