Kiwifruit - slow drying
I think you were just lucky in that they didn't go moldy or rot in your refrigerator.  So, if you want more control, it would be a simple matter of peeling, slicing and dehydrating.  You can do this in an oven set on it's lowest temperature, or more reliably by using a food dehydrator. You can certainly experiment with whole fruit or larger chunks, but I think slices are the way to go for ease of use and storage.