Fill a large pot with a few inches of water and fit it with a steamer basket. Bring the water to a boil, then lower it to a simmer. Place the tempeh in the steamer basket, cover the pot, and steam for 10 minutes.

While the tempeh is steaming, in an airtight storage container that’s big enough to hold all the tempeh, whisk together the vinegar, tamari, maple syrup, oil, and garlic powder (up to 1⁄2 teaspoon if you prefer a stronger garlic flavor)

Add the steamed tempeh, cover the container with a tight lid, and shake the container to evenly coat the tempeh with the marinade. Allow the tempeh to marinate in the fridge for at least 1 hour and up to overnight.

Preheat your oven to 375°F / 190°C and line a baking sheet with parchment paper. Remove the tempeh from the marinade with tongs or a slotted spoon, letting the excess drip off, and then transfer it to the sheet, reserving the marinade.

Bake the tempeh cubes for 10 minutes. Remove the tempeh from the oven and brush the tops with the reserved marinade. Flip the cubes and return the sheet to the oven. Bake until crispy at the edges, 10 to 15 minutes more.

Use right away or store the tempeh in an airtight container in the fridge for up to 5 days or in the freezer for up to 4 weeks.