Preheat the grill.
In a saute pan over medium-high heat, melt the butter. Add the onion and garlic and saute until translucent. Add the salt, chives, lemon zest, lemon juice, dill, and wine and reduce by 1/3. Add olive oil and capers and stir. Remove from the heat.
In a large foil square, place a spoonful of sauce. Add 1 piece of fish, cover with more sauce, and wrap tightly. Repeat with the remaining fish. Place the packets on the grill and grill for 3 minutes on each side.
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