You can't beat a simple vinaigrette based on fine quality olive oil and champagne vinegar for flavor and elegance. The mixture of sweet, delicate lettuces makes a terrific palate cleansing course in the classic French tradition. The tender baby greens benefit from a light, bright tasting dressing and need no other adornments.
Place the olive oil, vinegar, salt, and pepper in a small glass jar and seal the lid tightly. Shake vigorously to combine. Taste and adjust seasoning as needed.
Pour the dressing into a large salad bowl. Add the greens and toss gently to coat the leaves. Divide among 4 small plates and serve immediately.