Juice oranges until you have ½ cup worth of orange juice.
Combine orange juice, 1 tablespoon soy sauce, ¼ teaspoon ginger powder, ¼ teaspoon garlic powder, rice vinegar, 1 teaspoon brown sugar, ¼ teaspoon turmeric powder, and ½ tablespoon orange zest
Slice 8 ounces of tempeh into triangles or cubes, add them to the marinade and let it soak for at least 1 hour or up to overnight.
After marinating the tempeh, remove the pieces from the marinade, but do not throw out the marinade!
Heat a pan with 1 tablespoon of oil and add the pieces of marinated tempeh.
Cook on medium-high heat until each side is browned and the tempeh is cooked through. About 3-5 minutes each side.
Heat the orange marinade in a separate pan or saucepot.
In a small bowl or measuring cup, create a slurry of ½ tablespoon of cornstarch with 2 tablespoons water. Ensure there are no clumps and then add this to the marinade as it is heating up.
Add ½ tablespoon of soy sauce, ¼ teaspoon ground ginger, ¼ teaspoon of garlic powder/garlic salt, and ¼ teaspoon of brown sugar.
Combine these in the sauce and turn off the heat once the sauce has become very thick.
Add the cooked tempeh to the thickened sauce and toss until all the pieces are coated in the sticky orange sauce.
Serve over rice, salad, rice noodles, etc. Optional garnish with cilantro!