For the patties, preheat the oven to 425°F. Line a baking sheet with parchment paper.
Begin by preparing your flax egg. Add 1 tablespoon of ground flaxseed with 3 tablespoons of water- let sit for 5-10 minutes until a yolky consistency has formed.
Use a cheese grater or the grater attachment on a food processor. Grate the potatoes, measure out 2 cups. Next, grate the broccoli, and measure 1/2 cup.
Combine all ingredients in a bowl- mix thoroughly. The batter will be quite wet and sticky- this is normal.
Measure out a 1/4 cup of batter, empty it into your hands and then onto parchment paper- should form 7 patties. Flatten and re-form the patties, as desired.
Option to brush the patties with a bit of oil before putting in the oven.
Bake in the oven for 20 minutes. Then flip the patties and bake for another 15 minutes.
For the sauce: combine all ingredients in a bowl and mix!