Grilled Salmon Fillets with Herb Butter

INGREDIENTS

• 1 Tbs. finely chopped fresh chives
• 1 Tbs. finely chopped fresh dill
• 1 Tbs. finely chopped fresh tarragon
• Kosher salt and freshly ground pepper, to taste
• 8 Tbs. (1 stick) unsalted butter, at room temperature
• 1/4 lemon
• 6 skin-on center-cut salmon fillets, each about 8 oz. and 1 inch thick, pin bones removed
• 1/4 cup mayonnaise, homemade (see related recipe at left) or store-bought
• 2 tsp. ground cumin
• 2 tsp. ground coriander