In a small bowl, mix together the lemon and water. Add in the diced apple and toss to cover the apple well. Drain the apple, discarding the lemon water, and set apple aside.
To make the salad, layer the salad ingredients in the order listed into the jar (put in the apple right after the dressing), packing in as much spinach or kale as you need to create a tight pack. Cover the jar, and place it in the fridge for up to 5 days.
To eat, dump the entire contents of the jar into a bowl, toss, and enjoy!
Notes
If you add the apple to the jar, I recommend eating within 24-36 hours. If you want to have it last longer, add the apple right before serving.