Wash the strawberries gently in room-temperature water, and dry each one with a paper towel. Set aside.
Chop up the dark chocolate and milk chocolate into small pieces; combine with a pinch of salt in a heat-resistant bowl.
Place the bowl with the chocolate over a saucepan of simmering water, and stir until melted. You can also melt the chocolate in the microwave for 20 seconds at a time, stirring after each time. The chocolate will melt inside before it melts outside, so be sure to stir well after each burst in the microwave.
In a separate dish, melt the white chocolate using the same method.
Take one strawberry at a time by the leaves or stem (if the stem is too short, you can insert a toothpick gently into the strawberry and hold the toothpick). Dip into the melted dark chocolate. Rotate gently to coat.
Hold the strawberry over the dish of melted chocolate for a moment, and let the excess drip off. Gently shake as needed to remove excess.
Lay the dipped strawberries on a wire rack and allow the chocolate to set before sprinkling on any toppings.
When the chocolate has set, drizzle white chocolate over the strawberries with a fork. If using hazelnuts, gently dip the strawberry in a bowl of roasted, chopped hazelnuts.
Allow the strawberries to set for about 2 hours at room temperature before serving.