Prepare the Big Mac Sauce: In a bowl, mix vegan mayo, organic ketchup, sweet relish, apple cider vinegar, onion powder, garlic powder, and paprika. Stir until well combined.
Prepare the Vegetables: Chop iceberg lettuce and white onion.
Prepare the Impossible Meat: In a bowl, mix 12 oz. of Impossible Meat with 1 tbsp vegan Worcestershire sauce and ½ tsp salt. Mix thoroughly.
Form the Meat Patties: Weigh out 2 oz. portions of the meat mixture and place each on a soft corn taco shell. Use a spatula to spread the meat evenly on one side of each shell.
Preheat the Grill: Preheat your Blackstone grill to 350°F. Spray the grill top with avocado oil and check the temperature.
Cook the Tacos: Place all 6 taco shells on the grill, meat side up, to get them crispy outside. Cook for about 5 minutes. Flip the shells and press them with a spatula to create a nice crust. Flip them over again to ensure even cooking.
Assemble the Tacos: Bend the shells into taco holders. Dress the tacos with shredded lettuce, chopped onions, and the prepared Big Mac sauce.