Marinated Swordfish with Lemon-Chive Butter

For the Marinade:

1/3 C. Champagne vinegar or other white wine vinegar

1 T. fresh lemon juice

1 tsp. Dijon mustard

1/3 C. extra-virgin olive oil

1/4 C. vegetable oil

1/2 C. minced red onions

3 T. minced lemon balm or verbena or zest of 1 lemon, minced

1 tsp. minced fresh thyme leaves, preferably lemon thyme, or 1/2 tsp. dried

2 T. minced fresh chives

1/2 tsp. freshly ground black pepper

2 lb. swordfish steaks, 1 inch thick, cut into 4 serving pieces

 

1/4 C. (1/2 stick) unsalted butter, softened

1 T. minced fresh chives

1 tsp. minced lemon balm or verbena or 1/2 tsp. minced lemon zest

Kosher salt

 

In a glass or ceramic dish large enough to hold fish in a single layer, combine vinegar, lemon juice and mustard. Vigorously whisk in both oils to make a thick emulsion. Blend in onions, lemon balm or verbena or zest, thyme, chives and pepper. Thoroughly coat swordfish with marinade, cover with plastic and refrigerate for several hours. Bring to room temperature before proceeding. Meanwhile, make herb butter: Blend softened butter with chives and lemon balm or verbena or zest. Place on a sheet of wax paper and roll into a log. Chill until needed, at least 2 hours. Thoroughly clean the surface of a gas or charcoal grill with a metal brush; coat the rack evenly with vegetable oil. Preheat the grill until hot. Remove the fish from marinade, and sprinkle with salt. Place fish on the prepared grill, cover and cook for 5 minutes. Turn fish, cover and cook for 5 minutes more.  Place a slice of herb butter on each portion or fish and serve