When I asked the soba shop the trick to making their tempura so crispy, they told me that they add vinegar to the batter and don't use eggs. I experimented with the proportions and came up with this recipe.

The batch of batter that you get from the amounts listed will be more than you need, so you can also fry up 1-2 more ingredients (such as shrimp). If you have a small amount to fry up, reduce the proportions accordingly. Recipe by Ri-karu