Season the salmon fillet with salt and pepper on both sides.
Heat a non-stick skillet over medium-high heat with a drizzle of olive oil.
Place the salmon in the skillet skin-side down and sear for about 4-5 minutes; then, flip and cook for another 3-4 minutes until the fish is just cooked through.
While the salmon is cooking, prepare the lentil salad by combining the cooked lentils, red bell pepper, cherry tomatoes, and red onion in a bowl.
Drizzle the lentil mixture with olive oil and lemon juice, add minced garlic, and gently toss to combine. Adjust seasoning with salt and pepper.
In another pan, quickly sauté the spinach with a dash of olive oil and a pinch of salt until just wilted, about 2 minutes.
Plate the lentil salad and sautéed spinach on a serving dish, and top with the seared salmon fillet.
Serve immediately, enjoying the balance of zesty lentils, tender salmon, and fresh greens.