Cut 9 oz tempeh into approximately 1-inch pieces.
Bring a pot of water to a boil, add the tempeh, then reduce to a simmer.
Cook for 15 minutes, adjusting the heat as needed to maintain a simmer.
Drain and discard the cooking water, then add the tempeh to a blender.
Add 1 cup water, 1/2 cup nutritional yeast, 1/4 cup extra virgin olive oil, 2 tablespoons lemon juice, 1 teaspoon salt, 1/2 teaspoon garlic powder, and 1/2 teaspoon onion powder to the blender.
Blend until smooth, scraping down the sides of the blender as needed.
Add 2 tablespoons tapioca starch, then blend to combine.
Transfer the mixture to a pot on the stove set to medium heat.
Whisk frequently while cooking for 3-6 minutes or until it becomes thick and stretchy, then immediately remove from the heat.
Let the mixture rest for at least 20 minutes (it will thicken more as it cools) then use in dishes such as grilled cheese, lasagna, or pizza.
Or transfer the mixture to a container and refrigerate for at least two hours, then use as a spread on toast or crackers.