Cut off the ends of plantains. Then cut plantains into 2 inch pieces.
Cut the 2 inch pieces in half lengthwise and remove the skin.
Preheat a skillet over medium heat with enough avocado oil covering the bottom of the skillet.
Once heated, add the plantains and cook on each side for 3-4 minutes or until lightly browned and cooked through.
Remove plantains from skillet, flatten the plantains using something with a flat surface, and then refry in the same skillet. (Replenish avocado oil if you need to.)
Refry plantains for 2-3 minutes one each side or until golden brown.
Remove tostones from the skillet, place on a paper towel lined plate, and salt immediately.
While tostones cool, melt the chocolate chips with the coconut oil in the microwave or a saucepan.
Once melted, coat half of the tostones on both sides with the chocolate and then sprinkle the chopped hazelnuts while the chocolate is still wet.
Repeat the process until all of the tostones are coated.
Refrigerate in a single layer for at least 1 hour or until the chocolate has solidified.