Roasted Hazelnut soil? I had a really creative dish at a local restaurant that was radishes that where dipped in butter and then rolled in hazelnuts that looked like dirt. Obviously it wasn't dirt but hazelnuts that had been ground up and then cooked some way to make it look like dirt.

Any ideas on how to replicate this?

Here is a pic
Dry roast the nuts in a pan or skillet until golden, keep them moving at all times. Let them cool completely on a paper towel. Grind them to the right particle size you need. Spread them thinly and evenly on an oven tray and bake at somewhere around 140-160C. You will likely end up with some parts a little burnt. Or do whole nuts in a coffee roaster.