Place filberts in a medium bowl and add soy sauce and olive oil. Mix until all nuts are coated and the consistency is like a think soup. Set aside on the counter to marinate, 3-4 hours or overnight.
Preheat oven to 300 degrees Fahrenheit.
Place all filberts on a parchment lined baking sheet in one layer.
Bake in the oven for 20-30 minutes. Check after 20 and look for the skin to begin cracking and look darker (but not black).
Remove from the oven and allow to cool for at least 30 minutes.