Prepare the dressing:
In a small jar or bowl, combine olive oil, apple cider vinegar, honey, Dijon mustard, salt, and pepper. Shake or whisk until well combined.
Slice the apples:
Thinly slice the apples and, if desired, toss them in a little lemon juice to prevent browning.
Assemble the salad:
In a large mixing bowl, combine the mixed greens, sliced apples, crumbled cheese, dried cranberries, nuts, and red onion (if using).
Dress the salad:
Drizzle the dressing over the salad just before serving. Toss gently to coat all the ingredients evenly.