1. Add mushroom, carrot, and onion to a food processor, pulse about 20-30 seconds, until all veggies are the same size (about 1/8"). To food processor bowl, add all ingredients, except vital wheat gluten and pulse another 20-30 seconds until combined.
2. Dump mixture into a bowl and mix in vital wheat gluten by hand; knead for a minute or two. Allow burger mix to relax while you preheat oven to 300 degrees F.
3. Line a baking sheet with parchment paper and spray top of parchment with cooking spray. Take tangerine-sized portions of burger mix, form 3 1/2" patties, and place on baking sheet at least 1" apart.
4. Bake for 25 minutes. Carefully flip patties and bake another 15 minutes. Move patties to wire rack to cool. Cut out burger-sized pieces of parchment to place between patties before you freeze or refrigerate them.
5. To cook, allow patties to thaw, spray skillet with cooking spray or coat with oil, and cook over medium heat for 4-5 minutes on each side. Or nuke frozen patty in the microwave for 60-90 seconds.
Source of recipe: I had an idea of making veggie burgers with veggie ground beef, but was skeptical of it. Not anymore. These are moist (not rubbery like most veggie burgers) and they develop a nice, smoky crust when you grill them.