Thinly slice the tempeh.

Prepare the marinade by combining all ingredients listed under 'Tempeh Marinade' above in a bowl. Whisk to combine.

Add the sliced tempeh to the bowl and gently toss to coat the tempeh with marinade.

Cover and place the bowl in the fridge. Allow the tempeh to marinate for at least 2-3 hours or overnight if possible. Gently toss once in between while marinating to get even coating.

When you are ready to bake the tempeh, preheat the oven to 350 degrees and remove the marinated tempeh from the fridge.

Line a baking sheet with parchment paper . Place the slices of marinated tempeh on the lined baking sheet in a single layer.

Using a basting brush , brush some of the leftover marinate in the bowl once more on each slice of tempeh.

Bake for 10-15 minutes until browned and crispy. Remove from oven, flip each slice of tempeh, brush leftover marinade on top of each slice once more, and place back in the oven for an additional 10-15 minutes to cook the other side. Note that oven temperatures may vary so be sure to check while baking and flip the tempeh over after it's browned and crispy to avoid burning the tempeh.

Completely mash the avocado in a bowl. Season with a little salt and pepper (optional).

Grill two pieces of bread on both sides on a pan with a little olive oil or vegan butter until golden brown. Let them cool slightly to avoid moisture build-up on the bread.

Spread a layer of the mashed avocado on one slice of bread. Top with a layer of baby arugula leaves, followed by 4 pieces of the prepared crispy tempeh, and a layer of sliced tomatoes.

Spread 1-2 tbsp of the prepared Roasted Garlic Truffle Aioli on the other slice of bread and close the sandwich. Press together gently.

Repeat to make two more sandwiches. Cut the sandwiches in half and enjoy!