Peel beets and shred with the shredder attachment of your food processor, then set aside. Change the attachment to a metal blade. Pulse the brown rice, shredded beets and lentils about 15 to 20 times, until the mixture comes together, but still has texture. It should look a lot like ground meat.
Now transfer to a mixing bowl and add all the remaining ingredients. Use your hands to mix very well. Everything should be well incorporated, so get in there and take your time, it could take a minute or two.
Place the mixture in the fridge for a half hour to chill.
Preheat a cast iron pan over medium-high. Now form the patties. Each patty will be a heaping 1/2 cup of mixture. To get perfectly shaped patties, use a 3 1/2 inch cookie cutter or ring mold. Otherwise, just shape them into burgers with your hands.
Cook patties for about 12 minutes, flipping occasionally. Do two at a time if your pan isn’t big enough. Use a little spray olive or avocado oil if needed. Burgers should be charred at the edges and heated through.
Serve on a whole grain bun with all the fixins!