Preheat the oven to 400ºF. Line a baking sheet with parchment paper.
Rinse the red lentils and then bring the lentils and the 1 1/4 cups of water to a boil. Turn the heat to a simmer once boiled and leave uncovered for 10 minutes or until the red lentils are cooked. If there is excess water one the lentils are done, drain the water.
Sauté the onion and garlic in oil over medium heat until golden brown.
Wash, peel and grate 1 medium sweet potato, it should roughly measure 1 cup.
Add all the ingredients (except the oat flour) to the food processor. Pulse a few times to that the mixture becomes combined yet still has a chunky texture. Remove from the food processor and add to a bowl. Stir in the oat flour. The dough should be slightly wet still but holds together.
Measure out 5 patties (1/3 cup each). Using your hands form small circular discs with the patties. Place in the oven for 15 minutes. Flip the patties after 15 minutes and put them back in for 12-15 minutes more. The inside should still slightly underdone when you first take them out of the oven. The outside should be brown and crispy. Let the patties cool for 5-10minutes then enjoy.