Add all the ingredients to a small mixing bowl and whisk together.
Pour over sliced tempeh and allow to marinate for at least 20-30 minutes.
Remove tempeh from marinade and cook the tempeh in your preferred cooking method (see above article for cooking options).
In a skillet over medium heat, add the leftover marinade. In a small bowl, whisk together the cornstarch with cold water to form a slurry and add to the marinade. Stir in and bring to a boil.
Boil for a minute, then turn down to a simmer and cook for 3-5 minutes until it thickens, stirring constantly.
Add your cooked tempeh into the marinade and stir to coat. The thickened marinade will stick to the cooked tempeh and create a super flavorful sticky coating. Yum!