Preheat the oven to 350 degrees Fahrenheit.
Add 1 teaspoon garlic powder, 1 teaspoon onion powder, 1 teaspoon smoked paprika, 1 teaspoon ground coriander, 1 teaspoon ground mustard, 1/2 teaspoon black pepper, 1/3 cup silken tofu, 1/3 cup beet juice, 2 1/2 tablespoons soy sauce, 1 tablespoon tomato paste, 1 tablespoon balsamic vinegar, 2 teaspoons olive oil, and 1/4 cup nutritional yeast to a blender.
Blend until smooth.
Transfer that mixture to a large mixing bowl.
Spoon 1 cup vital wheat gluten into a measuring cup (don’t scoop), then add it to the mixing bowl.
Mix with your hands until combined, then knead for 2-3 minutes (I recommend wearing kitchen gloves to avoid staining your hands if you’re using beet juice).
Transfer the dough to a 9x13-inch baking dish (or similar size) lined with parchment paper, then shape it into an oval or rectangle. To ensure the best texture, make sure it isn’t taller than about 2 1/2 inches.
Pour 1/3 cup cold water into the corner of the baking dish (not directly on the dough).
Cover the baking dish with an oven-safe lid or aluminum foil, then bake for 45 minutes.
Let the pastrami cool to room temperature before slicing and serving (the texture improves as it cools).