Cut the tempeh into cubes, place in a steamer basket, and set over a pot with 1-inch of water. Bring the water to a simmer, cover, and steam for 10 minutes. This helps the tempeh become tender and ready to soak up more flavor from the marinade.

In a small bowl, whisk together the tamari, vinegar, maple syrup, olive oil, sriracha, and several grinds of pepper. Place the tempeh in a shallow dish and pour the marinade on top to coat. Marinate for at least 30 minutes.

Preheat the oven to 425°F and line a baking sheet with parchment paper.

Arrange the cubes in a single layer on the baking sheet, reserving the excess marinade.

Bake for 10 minutes. Remove from the oven and brush more of the marinade onto the cubes. Bake for 10 more minutes, or until the cubes are charred around the edges. Enjoy on salads or grain bowls.