Preheat oven broiler. Place fish on rimmed baking sheet lined with parchment paper, season with salt and freshly cracked black pepper to taste, and broil until cooked through, 6 to 7 minutes. Let cool slightly, then flake flesh into large pieces and set aside.
In bowl, whisk together yogurt, olive oil, 1 Tbsp lemon juice, curry powder, and salt.
In 4 individual salad bowls, place cooked lentils and toss with remaining lemon juice. Top with radish, cucumber, and trout pieces. Drizzle on yogurt dressing and top with arugula.
Recipe Notes
Per serving: 413 calories; 42 g protein; 18 g total fat (3 g sat. fat); 25 g total carbohydrates (6 g sugars, 9 g fiber); 271 mg sodium