Initial Preparation & Aromatic Base: Preheat your oven to 400°F (200°C). Pat the salmon fillets completely dry with paper towels and set aside. In your oven-safe skillet over medium heat, warm 1 tablespoon of extra virgin olive oil. Add the chopped red onion and bell pepper, sautéing for 5-6 minutes until softened. Add the minced garlic and cook for another minute until fragrant.
Lentil Infusion: Stir the rinsed lentils, dried oregano, red pepper flakes, sea salt, and black pepper into the skillet with the aromatics. Pour in the low-sodium vegetable broth, stir to combine, and bring the mixture to a simmer.
Ragoût Construction: Once simmering, reduce the heat to low, cover the skillet, and let the lentils cook for 15 minutes. The lentils should have absorbed most of the liquid but still have a slight bite.
Vegetable Medley Integration: Uncover the skillet and stir in the halved cherry tomatoes, rinsed olives, and rinsed capers. The mixture should be thick, not watery.
Salmon Positioning & Seasoning: Gently nestle the salmon fillets, skin-side down, into the lentil and vegetable ragoût. Drizzle the remaining 1 tablespoon of olive oil over the tops of the fillets.
Unified Roasting: Transfer the entire skillet to the preheated oven. Roast, uncovered, for 15-18 minutes. The salmon is done when it flakes easily with a fork or reaches an internal temperature of 145°F (63°C) for medium-well. For a rarer finish, check at 12 minutes.
Final Flourish & Serving: Carefully remove the skillet from the oven. Squeeze the juice of half the lemon over the entire dish. Garnish generously with the fresh parsley and the zest of the whole lemon. Serve immediately, spooning a bed of the lentil ragoût onto each plate and topping it with a salmon fillet.