It could be a simple bias test where you use your own bio assessment for the flushed vs non flush. This might assume a cure, or you could consume the plants as soon as dried.
If your plants
need a cure to be consumed I'd recommend a flush
For lab tests, no cure necessary. Once material is dry submit to lab gram for gram flushed for fed.
Flushing is however one wants to define it within context of application.
For this experiment semantics need to be set aside and flushing be defined as NOT FEEDING.
For hydro systems a flush would be an entire res change of RO/DI/Distilled water ph'd
For coco systems a flush would constitute passing enough RO/DI/Distilled water to have runoff. I look for 20-50% container volume worth of runoff.
Nothing suggests that either is exhaustive or exclusive. Both methods of evaluation can be done in parallel, and other suggestions appended to methods of test.