Grilled Salmon with Dill Pickle Butter

Bahan-bahan (4 porsi)

• 4 tablespoons unsalted butter, (at room temperature)
• ¼ cup finely diced dill pickles
• 1 teaspoon minced fresh tarragon
• ½ teaspoon Dijon mustard
• salt and freshly ground black pepper
• Four 6-ounce salmon fillets ((with skin))
• extra virgin olive oil, (for rubbing)