The subtle spiciness of French Basque piment d’Espelette chile powder is perfect for this butter, though crushed red pepper flakes make a fine substitute. If your market is out of good salmon steaks, try substituting halibut steaks.

For the butter:

1/4 lb. (8 Tbs.) unsalted butter, softened to room temperature
3 Tbs. finely chopped fresh cilantro
2 tsp. fresh lime juice
1 tsp. coriander seeds, lightly toasted and coarsely ground
3/4 tsp. freshly grated lime zest
1/2 tsp. coarse sea salt, like fleur de sel or sel gris
1/2 tsp. piment d’Espelette chile powder or crushed red pepper flakes
1/4 tsp. minced garlic
For the salmon:

1-1/2 Tbs. olive oil; more for brushing the grill
Four to six 1-1/4-inch-thick salmon steaks (6 to 8 oz. each)
1 tsp. kosher salt
Make the butter:
Beat the butter in a small bowl with a spoon to loosen it. Mix in the remaining ingredients until they’re evenly distributed. Scrape the butter onto a sheet of parchment or plastic wrap and roll it into a neat log, using the parchment or plastic as a guide. Twist the ends and refrigerate the butter until firm, about 1 hour. Keep the butter chilled until ready to use.

Grill the salmon:
Clean and oil the grates on a gas grill and heat the grill to medium high, or prepare a medium-hot charcoal fire.

Meanwhile, generously coat both sides of the salmon with the oil and season both sides with salt. Let the salmon sit at room temperature for 15 minutes (while the grill heats). Grill the salmon steaks directly over the heat source (covered on a gas grill, uncovered on a charcoal grill), without touching, until they have good grill marks, 2 to 4 minutes. Flip the steaks and grill until the second sides have good grill marks and the fish is done to your liking, another 2 to 4 minutes. (Check for doneness by slicing into one of the thicker pieces.) When the salmon is nearly done, remove the butter from the refrigerator and slice it into thin rounds.

The second the salmon comes off the grill, top each steak with two rounds of butter. Serve immediately.

Serving Suggestions
Serve with Grilled Corn Salad with Cherry Tomatoes, Arugula, and Ricotta Salata.

nutrition information (per serving):
Size : based on six servings, Calories (kcal): 410, Fat (kcal): 27, Fat Calories (g): 240, Saturated Fat (g): 12, Protein (g): 40, Monounsaturated Fat (g): 9, Carbohydrates (mg): 1, Polyunsaturated Fat (mg): 3.5, Sodium (g): 450, Cholesterol (g): 105, Fiber (g): 0,