If fish is not already cooked, poach, bake, or pan-sear about 12–16 oz of white fish until opaque and flaky (internal temp ~145°F / 63°C). Allow to cool slightly, then use a fork to flake into bite-sized pieces, yielding about 2 cups.

Prepare vegetables

Rinse and thoroughly dry the mixed salad greens. Halve the cherry tomatoes, slice the cucumber, thinly slice the red onion, and finely dice the celery. Quarter the hard-boiled eggs if using.

Assemble

In a large bowl, combine the mixed greens, cherry tomatoes, cucumber, red onion, celery, capers, and chopped parsley. Gently fold in the flaked fish so it distributes without breaking up too much. Add the quartered eggs on top if using. Reserve lemon wedges for serving.

Dressing

In a small bowl or jar, combine the lemon juice, Dijon mustard, white wine vinegar, honey (or maple syrup), minced garlic, salt, black pepper, and optional red pepper flakes. Whisk or shake to combine.

Slowly drizzle in the extra-virgin olive oil while whisking (or add to the jar and shake vigorously) until the dressing emulsifies and thickens slightly. Taste and adjust seasoning with additional salt, pepper, or lemon juice as needed.

Drizzle about half the dressing over the assembled salad and gently toss to coat. Add more dressing as desired, taking care not to overdress—the fish should remain the salad's focal point.

Serve immediately with lemon wedges alongside for extra brightness.