Place the quinoa in a small saucepan. Cover the quinoa with ⅔ cup filtered water. Turn the heat onto medium high and bring quinoa to a boil. Simmer until all water has been absorbed, about 15 minutes. Set aside.
While quinoa is cooking, in a large bowl, mash the chickpeas with a potato masher or fork. There should still be some slightly larger pieces of chickpea. Set aside.
Grind the sunflower seeds in a food processor or the dry container of a Vitamix (or similar). It should look like almond meal with a few whole seeds remaining. Transfer ground sunflower seeds to the bowl with the chickpeas. Add the cooked quinoa to the bowl as well.
Rinse out the saucepan, and return it to the heat. Add the olive oil to the pan and let it heat up. Add the shallots to the pan and saute until slightly soft, about 3 minutes. Add the garlic and chili powder to the pan. Stir and cook until garlic is fragrant, about 30 seconds. Remove the shallot mixture from the heat and add it to the bowl with the chickpeas and quinoa.
To the chickpea mixture, add the sun dried tomatoes, tomato paste, Worcestershire sauce, grated beetroot, lemon zest, hot sauce, salt, and pepper. Stir mixture with a spatula thoroughly to combine, or use the back of the tines of a fork to “rake” the mixture together. Sprinkle the oat flour over to of the mixture. With your hands, bring the burger mixture together one more time.
Divide the burger mixture into either 4 or 6 patties, carefully but firmly patting them together with your hands. Set a piece of parchment paper on a baking sheet. Lat the formed burgers on the lined baking sheet as you finish them. Cover the burgers with plastic wrap and let them set up in the refrigerator for at least 30 minutes.
Make the slaw: In a medium bowl, combine the celery, kale, lemon juice, olive oil, horseradish, salt, and pepper. Cover and place in the refrigerator until ready to serve.
Make the burger sauce: In a small bowl, whisk together the ketchup, mayonnaise, horseradish, and lemon juice. Cover and place in the refrigerator until ready to serve.
Preheat your grill to medium high. Lay a sheet of foil over the grates and grease the foil with either a spray oil or brushed-on olive oil. Place the burgers directly onto the foil and bring the lid down. Cook the burgers on one side for 8-10 minutes. Open the grill back up, very carefully flip the burgers over, and then close the lid again. Cook the burgers for another 8-10 minutes, or until you see some light charring.
Serve the bloody mary veggie burgers hot on toasted buns or in crisp butter lettuce leaves with the slaw and burger sauce. Enjoy!