Melt the chocolate according to package instructions or use the directions in How to Melt Chocolate.
Add about 1-2 tablespoons of the melted chocolate to the silicone mold.
Slice the strawberries into rounds. Make sure they are completely dry.
Add the slices to the mold. Make sure they don't sink completely into the mold.
Place the mold in the refrigerator to allow the chocolate to harden around the strawberries. Garnish with chopped walnuts if desired.
Notes
Just before adding the strawberries to the silicone mold, wipe them off with a paper towel to make sure they're as dry as can be. Melted chocolate and water do not mix!