Preheat oven to 425 degrees.
In a small bowl, stir together Nduja and 1 tablespoon olive oil until well combined. Place black bass in a baking dish and brush with nduja on both sides so it’s well coated. Place in the oven and bake until fish is opaque, 12-14 minutes. While fish is cooking, cut ramps in half, separating the bottom white part from the top leaves. Heat ½ tablespoon olive oil in a skillet. Add the white part of the ramps and sauté until tender; then add the leaves and continue to sauté until wilted.
Toss mustard greens with remaining olive oil and vinegar. Season with salt and pepper to taste and divide between two plates. Top with fish and sautéed ramps.