Whisk 1/4 cup of the lemon juice with the salt and pepper in a medium bowl. Gradually whisk in the oil to blend. Season the dressing with more salt and pepper as needed. (The dressing can be made 8 hours ahead. Cover and refrigerate. Return to room temperature and re-whisk before using.)
Toss the endive and apples with 2 tablespoons of the lemon juice in a large bowl to coat (the lemon juice will prevent the endive and apples from browning). Drizzle the remaining 1 tablespoon lemon juice over the avocado. Add the avocado, corn and cheese to the endive mixture. Gently toss the salad with enough dressing to coat. Season the salad with more salt and pepper as needed. Sprinkle the pomegranate seeds over the salad if desired and serve immediately.
Cut and add the avocado to the salad right before serving to avoid having the avocado turn brown in the salad.