Preheat your oven to 350°F / 175°C. Lightly coat a baking sheet with cooking spray.
In a large bowl, whisk together the miso paste and ¼ cup of water until smooth.
Add the grated tempeh and 1½ Tbs. of the canola oil, stirring to combine well.
Sprinkle in the vital wheat gluten and guar gum, and mix until a cohesive dough forms.
Mound the tempeh mixture onto the prepared baking sheet, cover it loosely with foil, and bake for 20 minutes, or until it's firm and heated through.
While the tempeh bakes, heat the remaining 1½ Tbs. of oil in a large skillet over medium heat.
Add the grated mushroom, beet, onion, carrot, corn, bell peppers, and minced garlic.
Sauté for about 10 minutes, stirring occasionally, until the vegetables are tender and fragrant.
Transfer the cooked vegetables and the baked tempeh mixture to a food processor. Pulse 6 to 7 times, just until the mixture is combined but still has some texture. Be careful not to over-blend into a paste.
Form the mixture into 8 evenly-sized patties.
Place them on a plate or baking sheet, cover with plastic wrap, and refrigerate for at least 4 hours, or preferably overnight. This step is crucial for the flavors to meld and the patties to firm up.
When ready to cook, preheat your grill to medium heat.
Brush both the burgers and the grill rack with a little oil to prevent sticking.
Grill for 8 to 10 minutes per side, or until nicely browned and heated through.
Serve immediately on your favorite buns with all the fixings.
Don't skip the chill time! Refrigerating the patties is essential. It allows the vital wheat gluten to fully activate, ensuring the burgers are firm and hold their shape perfectly on the grill.
