Tips for Rhubarb Mincing
A Mincing with a knife is slow and tedious as the rhubarb is very fibrous.
This method takes a lot of effort. More effort than I wanted to put in.
B Using a hand chopper doesn't work too well.
It seems to squish the rhubarb (and it's long fibers) as opposed to chopping them.
C Combining of knife and hand chopping works well.
I found the easiest and fasted way to achieve a mince was to slice the rhubarb into 1/4 inch sized coins then use a hand chopper to mince.
D Using a food processor may be the easiest way for you to mince rhubarb.
Mine takes a lot of work. Lugging it out. Setting it up. Cleaning it. Blah.
My simplest method is C (stated above).
You may need to perform your own Really Rhubarb Experiment
to determine which tip works best for you.