Step 1Heat the oven to 450 degrees. Melt the butter in a small skillet or saucepan over medium-low heat. Add the hazelnuts and cook, stirring, until the smallest pieces begin to brown, 2 to 3 minutes. Immediately remove from the heat and continue stirring until the butter has cooled somewhat. Stir in the lemon zest, chives and one-half teaspoon salt.
Step 2Cut 8 (12-inch square) pieces of aluminum foil. Lay a piece of rex sole pale side up in the center of one and season the fish lightly with salt and pepper. Scatter about 2 ounces of sugar snap peas over top of the fish and spoon about 1 1/2 tablespoons of the hazelnut butter over the top. Crinkle the edges of the foil together to make an airtight package with some room left for expansion. Place the package on a baking sheet and repeat with the remaining ingredients.
Step 3Bake 15 minutes and then serve immediately, letting diners open their own packages. Pass the lemon wedges separately so diners can squirt a drop or two of lemon juice on the fish if they wish. Remove the fish bones before eating.