Add tempeh to a container and pour over soy sauce, apple cider vinegar, maple syrup. Seal container and shake to fully coat. Let marinate for at least 1 hour or up to 24.
Preheat oven to 350 degrees. Add tempeh to a sheet pan lined with parchment paper. Bake for 25-30 minutes.
Top toasted bread with avocado, tomato, mustard, lettuce, pickles and tempeh. Dig in.
Notes
This makes enough tempeh for 1-2 sandwiches depending on how big your tempeh block is and how hungry you are.