Grate onions and potatoes in Cuisinart. Transfer to a bowl lined with kitchen towel and squeeze out all the liquid.
Transfer onion and potatoes to a large, clean bowl.
Grate beets in Cusinart and add to the potato combination.
Add arrowroot starch, oatmeal flour, salt and pepper and combine well.
Pour enough avocado oil into a large pan enough to coat the bottom. You will have to add more oil as you continue frying the latkes.
Form the potato-beet mixture into flat pancakes in the palm of your hands and place in frying pan.
Fry latkes 3-4 minutes on each side, then flip to the other side.
Place on a prepared baking sheet and place in oven set to 350 degrees F for 15 minutes, then transfer latkes to a plate lined with paper towels to absorb the excess oil.
Enjoy!