Lightly season both sides of the salmon fillet with salt and pepper. Drizzle a small amount of olive oil on both sides to coat.
Heat grill to medium-high. Add a small amount of vegetable oil on a folded piece of paper towel, and then carefully grease the grill grates.
Once the grill is nice and hot, add the salmon fillets. Cook uncovered about 4 to 5 minutes on each side until flaky (about 130-140°F).
Remove the salmon from the grill and transfer to a clean plate, cover to keep warm. Remove the skin if still attached.
In a large bowl add salad ingredients; lettuce, tomatoes, cucumber, red onion, bell pepper, cheese, and walnuts. Set aside.
Lemon Basil Vinaigrette
Add lemon juice, zest, olive oil, mustard, honey, garlic, basil, oregano, salt, and pepper in a blender.
Blend until well combined and a slightly thick and opaque dressing is achieved, about 30 seconds. Add more salt and pepper as desired.
To Serve
Toss salad with enough dressing to coat the ingredients, you will have extra dressing. Evenly divide mixture among four bowls and top with 1 salmon fillet. Drizzle each salmon with more dressing if desired.