Rinse the mixed greens thoroughly in cold water and spin or pat dry until mostly moisture-free. Halve the cherry tomatoes. Peel and slice the cucumber into 1/4-inch half-moons (for 1/2 cup sliced cucumber total). Thinly slice the red onion into very fine half-rings and separate them so they won't clump.

Assemble salad

Place the dried mixed greens in a large bowl. Scatter the halved cherry tomatoes, sliced cucumber, and thinly sliced red onion over the greens. Add the croutons on top. If using, chop the fresh parsley roughly and sprinkle over the salad as a garnish.

Simple vinaigrette

Make the dressing

In a small bowl or jar combine the red wine vinegar, Dijon mustard, honey (or maple syrup), minced garlic, salt, and black pepper. Whisk together while slowly drizzling in the olive oil until the dressing emulsifies and becomes slightly thickened. Taste and adjust seasoning—add a pinch more salt or a few drops of vinegar if needed.

Dress the salad

Lightly drizzle about two-thirds of the vinaigrette over the assembled salad and toss gently with salad tongs until the greens and vegetables are evenly coated. Add the remaining dressing to individual servings if anyone prefers more. Sprinkle additional croutons on top just before serving so they stay crisp.