Preheat and prep: Heat a grill or grill pan to medium-high. Pat the salmon dry with paper towels.
Brush lightly with olive oil and season with salt, pepper, and a little lemon zest.
Make the dressing: In a small jar, combine 3 tablespoons olive oil, 1.5 tablespoons balsamic vinegar, Dijon, honey, lemon juice (about 1 tablespoon), garlic, a pinch of salt, and pepper. Shake until emulsified. Taste and adjust sweetness or acidity.
Toast the nuts: Add nuts to a dry skillet over medium heat.
Stir until fragrant and lightly golden, 3 to 4 minutes. Set aside to cool.
Grill the salmon: Oil the grill grates. Place salmon skin-side down and cook 4 to 5 minutes.
Flip and cook another 2 to 4 minutes, depending on thickness, until the center is just opaque and flakes easily. Aim for 125–130°F for moist, medium salmon. Rest for 3 minutes.
Build the salad base: In a large bowl, add spinach, sliced strawberries, cucumbers, and red onion.
Drizzle with a little dressing and toss gently to coat. You want the greens glossy, not drenched.
Add creamy and crunchy: Top with avocado, goat cheese or feta, and cooled toasted nuts. Sprinkle chopped basil or mint, if using.
Finish with salmon: Flake or slice the warm salmon and place it over the salad.
Spoon a little extra dressing over the fish for shine and flavor.
Serve: Grind a little fresh pepper on top and add a final squeeze of lemon. Serve right away.