Toast bread (optional). In the meantime, heat skillet over medium heat. Once hot, add eggplant bacon (if using coconut bacon, no need to heat) and cook for 1-2 minutes. Then flip and cook for another 1-2 minutes on the other side until warmed through. Remove from heat and set aside.
To assemble sandwich, spread vegan mayo (or hummus) on the toasted bread slices. Then top one piece with Eggplant or Coconut Bacon, onion, tomato, and lettuce. Top with other piece of bread, slice (optional), and enjoy.
Could be made ahead of time (up to a few hours), but best when fresh.
*Nutrition information is a rough estimate for 1 sandwich calculated with 70-calorie (per slice) bread, Eggplant Bacon, and Aquafaba Mayo. *Spread pictured was hummus, but sandwich is even more delicious with vegan mayo!