Mix the flaxseed meal and water in a small bowl and set it aside for 15 minutes to thicken into a flax “egg”.
In the meantime, grab a medium pan, and add in 2-3 tablespoons of water, along with the onions, garlic, and celery. Sauté until translucent, about 4-5 minutes.
In a food processor, add in the flax “egg”, cooked vegetables and all of the remaining ingredients. Process for 30-45 seconds, or until all ingredients are blended together but still remain a bit chunky. Place into the refrigerator for 10 minutes.
Line a large sheet pan with parchment paper or a silicone baking mat. Remove the dough from the refrigerator and form mixture into patties using a mold or the top ring of a mason jar, then place them onto the lined pan. Each patty should be about 1/3 cup large, and this will result in 8 patties. Place in the refrigerator to set for 20 minutes.
Preheat oven to 375°F. Bake patties for 25 minutes, carefully flip, then bake for another 5-10 minutes or until browned.
Allow the patties to cool completely before assembling your burgers!
The nutrition facts are for the patties by themselves and do not take into consideration the optional ingredients.