To make sure the tempeh is packed with flavor you want to marinate it overnight and then bake it the next day. This will lock in the maximum flavor.
The first step is to steam your tempeh. Steaming is crucial because it helps the tempeh absorb the marinade and it will make for a better overall texture. You can use your Instant Pot or you can steam it on the stove. Whichever way you choose, cut your tempeh in half first, so you have two thick pieces.
To use your Instant Pot (IP), add 1 cup of water and the bay leaf to the pot and place the IP trivet on the bottom. Place the tempeh directly on the trivet and lock the lid into place. Make sure the nozzle is pointed in the sealing direction. Use the manual mode and set the timer for 5 minutes. Use the natural release method when the timer is up.
If using the stove, add two cups of water and the bay leaf to a pot, along with a steamer basket. Place the tempeh in the steamer basket and place a lid on the pot. Steam for 10 minutes. If you do not have a steamer basket you can gently simmer the tempeh and bay leaf directly in the water for 10 minutes.
When the tempeh is steamed, carefully slice both halves in half (lengthwise, through the middle) so that you have 4 thinner slabs in total. Set aside for now.
Make the marinade by placing all of the marinade ingredients into a bowl, and whisk until combined. Transfer the bay leaf from the IP or the pot and add it to the marinade.
Place the tempeh pieces into a container and pour the marinade over them. The marinade won’t completely cover the tempeh. This is okay - just flip the pieces over the next day so all sides get some marinade goodness. Allow the tempeh to fully cool before you cover the container with a lid and place in the fridge until you bake it.
After the tempeh has done its thing overnight, bake at 350° for 20 minutes, flipping after 10 minutes.