Salmoriglio is a traditional Southern Italian sauce, and its pungent, acidic, herbal bite complements sweet summer tomatoes and light striped bass. Substitute the bass with another sweet, mildly fatty fish; too rich of a fish will overpower the sauce and potatoes.
How to Make It
Rinse garlic scapes, and pat dry with paper towels. Trim and discard woody ends and curly tops. Cut scapes into 1/8-inch-thick slices to equal 1/3 cup. (If using scallions and garlic, slice scallions to equal 1/3 cup, and thinly slice garlic to equal 1 teaspoon.) Combine garlic scapes, olive oil, lemon juice, 1 tablespoon water, dried oregano, red pepper, and bay leaf in a small saucepan. Season with salt and pepper. Bring to a simmer over medium. Reduce heat to low; cook, stirring often, until mixture is softened and darkened, about 5 minutes. Remove from heat; let cool 20 minutes. Discard bay leaf; stir in lemon zest.
Cut 2 shallow diagonal slashes across skin of each fillet; arrange in a single layer on a rimmed baking sheet lined with parchment paper. Brush both sides of fillets with 3 tablespoons garlic scape oil, and season with salt to taste. Stir tomato and fresh oregano into remaining oil; set salmoriglio aside.
Preheat oven to 450°F. Heat a large ovenproof skillet over medium-high until very hot, about 4 minutes. Add vegetable oil; heat until very hot, about 1 minute. Add fillets, skin sides down. Press fillets gently with a spatula. Reduce heat to medium, and cook until skin begins to brown around edges, about 4 minutes. Transfer skillet to preheated oven, and roast until fish is opaque and just cooked through, about 4 minutes. Flip fillets, and divide among 4 plates, skin sides up. Spoon salmoriglio evenly over each fillet. Sprinkle servings with arugula and parsley.