Avocado-Egg Breakfast Sandwich

Per serving:

2 slices whole grains bread (I use Dave's Killer Bread)
Dijon mustard on one piece of bread
Half mashed avocado on one piece of bread
Cucumber slices on top of avocado
1 sliced egg on top of that - Spice or hot sauce (optional)
Sprinkle lightly parmesan (or other grated hard cheese)
Spring mix or spinach on top
Put other piece of bread on top and cut