Add feta cheese to one slice of bread. On that same slice, add the mashed avocado and squeeze a generous amount of lemon juice on top. (Really, you can't go wrong with lots of lemon!) Then continue to layer this side with the roasted red bell peppers, baby spinach, and then the sliced red onion.
On the other slice, add a layer of sliced cucumber.
Assemble the sandwich and enjoy!
Notes
Calories will vary depending on the specific ingredients and quantities chosen, so they are not included in this recipe.*For this recipe I used Mezzetta Roasted Red Bell Pepper Strips and they were great.**This sandwich has a lot of moving parts, so I find that the larger slices of cucumber, the less likely the sandwich will fall apart in your hands while eating. I cut the cucumber into strips instead of circles.