Heat a skillet over medium heat and spray with oil. Slice the tempeh bacon in half and add to the skillet in an even layer. Cook until browned on both sides (approx. 2-3 minutes per side). Remove from the skillet and set aside.
Cut the ciabatta in half lengthwise and pull out some of the bread from the top half to make room for the filling. Spray with oil and toast under the broiler until browned.
Combine the pesto and mayo in a bowl and set aside. Add the avocado to a bowl and mash with a fork. Season with salt and pepper to taste. Set aside.
To assemble, spread the avocado on the bottom half of the ciabatta. Top with lettuce, tempeh bacon & tomatoes. Spread the pesto mayo on the top half of the ciabatta. Close the sandwich, slice into 4 sandwiches and enjoy.
Notes
I made my pesto from scratch with 1 cup fresh basil, 1/3 cup almonds, 1 lemon (juiced), salt & pepper. Add to a food processor and pulse until combined. Drizzle in oil with the motor running until your desired consistency is reached.