Jocelyn and I are having fun with soapnuts, and we discovered that just grinding them to a powder in a coffee grinder makes a nice, gently abrasive hand/dish soap.
It works best in conjunction with hot water since we're basically using the powder to make an instant version of the "tea" usually made with soapnuts.
Used on hands it produces a nice lather even when used with cold water, probably due to the heat caused by the friction of lathering and the heat inherent in warmblooded bodies.
When using the soapnut powder on dishes, however, higher temperature water is more important. For lightly soiled dishes merely warm water will get you enough lather no problem. For greasy dishes the water will need to be quite hot and you'll need to use more of the powder. For a particularly greasy bowl I heated some water in the tea kettle (not to boiling though that might have been even better), let it sit in the bottom of the bowl with some soapnut powder for a minute while I washed other stuff, then cleaned the bowl out easily. I ended up having to rinse it twice to get all the suds off.
We're keeping the powder in a little shaker-topped mason jar with some rice mixed in to absorb moisture and keep it from clumping. We'll see how well that works.
Hopefully the powder will have a longer shelf life than the tea.
FYI when you shake the shaker it produces a fine airborne power in addition to the stuff going onto your hands/sponge/dishes, which if inhaled will make you sneeze hard enough to knock a little piggy's house down.
It's worth mentioning that this doesn't make big mounds of foamy suds like commercial dish soaps do.
The first picture shows the suds I got after soaking the powder in hot water for about a minute and then scrubbing. They are small but seem to do quite a good job. The debris on the plate is from the soapnut powder itself and rinses off very easily.