Add tamari, oil, maple syrup, liquid smoke, paprika, garlic powder and pepper to a shallow dish. Whisk together with a fork and add tempeh slices. Cover and let marinate in the fridge for at least 1 hour or up to 3 hours.
Preheat oven to 400°F. Arrange tempeh slices in a single layer on a baking sheet lined with parchment paper or foil. You can pour the leftover marinade over tempeh or discard.
Bake for 15 minutes. Toss tempeh and bake for another 5-10 minutes, or until tempeh is crispy. Remove from oven and serve warm.