Wash and thoroughly dry the mixed salad greens using a salad spinner or by patting with paper towels. Trim any tough stems from romaine. Halve the cherry tomatoes, thinly slice the cucumber into rounds or half-moons, thinly slice the red onion, and peel and shred the carrot. Place all prepared vegetables in a large mixing bowl.

Add cheese and nuts

If using cheese, sprinkle the crumbled feta or grated Parmesan over the vegetables. If using nuts or seeds, toast them briefly in a dry skillet over medium heat for 2–3 minutes, stirring constantly, until fragrant and lightly browned; allow to cool slightly, then add to the bowl.

Dressing

In a small bowl or jar, combine the lemon juice (or vinegar), Dijon mustard, honey (or maple syrup), minced garlic, salt, and pepper. Whisk or shake to blend. Slowly drizzle in the olive oil while whisking continuously (or add oil to jar and shake vigorously) until the dressing is emulsified and slightly thickened. Taste and adjust seasoning: add more salt, pepper, or a touch more honey if needed.

Assembly

Just before serving, pour about half of the dressing over the salad and toss gently with salad tongs or two large spoons to coat the ingredients evenly. Add more dressing to taste (typically 1–2 tablespoons more for the quantities listed). Transfer the dressed salad to a serving bowl or divide onto two plates.

Serve immediately so the greens stay crisp. Leftover dressing can be stored in the refrigerator in a sealed container for up to 5 days; toss the salad only when ready to eat.