SLOWLY add in your baking soda. It will fizz up to watch out (hence the deep pot).
Add in your hazelnuts and boil for about 3 minutes.
Meanwhile, in a medium bowl, prepare some ice cold water (cold water with ice).
After 3 minutes, dip out a hazelnut with a slotted spoon and immediately put it in the ice cold water.
Using your fingers, try and remove the skins. If they easily come off, scoop out the rest of the hazelnuts and put into the ice cold water. If the skins are still tough to get off, then boil for another minute or two.
Once the skins are removed, place them on a clean towel or paper towel to dry.