First, preheat your oven to 400°F. In a small bowl, I mashed the miso paste and butter together with a fork until creamy. This mixture is what gives the salmon that rich, umami-packed coating.
Place the salmon filets on a baking sheet, skin side down. Spread the miso butter over the top and season lightly with black pepper. Bake for 15 minutes or until the salmon flakes easily with a fork.
While the salmon bakes, combine scallions, shallots, garlic, and red pepper in a bowl. Heat olive oil in a pan until hot but not smoking, then pour over the vegetables. Let it sit for 10 minutes, then stir in cilantro, red wine vinegar, and lemon juice.
Once the salmon is cooked, serve it on a bed of rice or greens. Spoon the sizzled scallion salsa verde over the top for a bright, fresh finish.