Place the mixed greens into a salad spinner and rinse thoroughly under cold water.
Spin the greens until completely dry and transfer them to a large salad bowl.
Finely chop the herbs and set aside.
Cut the cherry tomatoes in half if using, and add them to the greens.
In a small bowl, whisk together lemon juice, olive oil, Dijon mustard, and a pinch of salt and pepper until the dressing is smooth and slightly emulsified.
Pour the dressing over the greens and gently toss to coat every leaf evenly, watching for a bright, glossy appearance.
Sprinkle the chopped herbs over the salad and give it a final gentle toss to distribute the herbs evenly.
Taste the salad and adjust seasonings with more salt, pepper, or lemon juice as needed.
Let the salad rest for about 5 minutes to allow flavors to meld and greens to absorb the dressing.
Give the salad a final gentle toss, then serve immediately for maximum freshness and crunch.