Combine all ingredients in a cup and process with an immersion blender until smooth. Add more water to reach your desired consistency. How much you use will depend on how thick your tahini is to start, and the application you want to use it in (thinner for salad dressings, thicker for dips).
Recipe by Alison's Allspice at https://www.alisonsallspice.com/miso-tahini-sauce/