Kitchen sink is a composite, mounted under the solid-surface countertop. I assume it's some sort of heavy duty adhesive, like a clear silicone. Installed about 8 years ago.

Trouble is, there is mold that has crept into that interface; it's happened slowly over the years, but obvious enough now that it's ugly. Doesn't look like it's really deep, but then I really can't tell, just hoping it's not too deep.

Any ideas on remedies? I have no idea how wide the surface is that's under that counter, Was the original install sub-par? Looking at some installation videos I know, and can feel underneath there are clips holding the edges.

Do I just clean out as much silicone as I can, bleach the heck out of it, let it dry and re-caulk?

Here's a couple pictures:

 

Use a old toothbrush or other brush to clean the crevice.