How to Make It
Preheat oven to 400°F.
Cook bacon in a large skillet over medium-high heat for 1 minute. Add 5 ounces mushrooms; cook 5 minutes or until mushrooms wilt, stirring occasionally. Remove pan from heat; cool 10 minutes. Transfer mixture to a food processor; pulse 10 times or until a coarse mixture forms. (Do not puree.) Stir in pepper and 1/8 teaspoon salt.
Line a baking sheet with parchment paper. Sprinkle fillets with 1/8 teaspoon salt; top with mushroom mixture, pressing gently to adhere. Drizzle with 1 1/2 teaspoons oil; place on parchment. Bake at 400°F for 12 to 15 minutes or until desired degree of doneness.
Increase heat to broil, with oven rack 6 inches from heat. Broil fillets 3 to 4 minutes or until lightly browned.
Heat skillet over medium-high. Add 1 1/2 tablespoons oil; swirl. Add garlic and remaining 3 ounces mushrooms; cook 4 minutes or until mushrooms are soft. Add arugula; cook 1 minute or until slightly wilted. Sprinkle with 1/8 teaspoon salt. Serve with fish.