Shred sweet potato using either the coarse side of a box grater or the grater attachment of a food processor.
Heat a large rimmed skillet (we prefer cast iron) over medium heat. Once hot, add oil, onion, grated sweet potato, and kale. Sauté for 4-5 minutes, stirring frequently, or until the onion and sweet potato are tender and fragrant. Set aside.
To a large mixing bowl add sautéed vegetables, salt, and garam masala and stir. Then add rice flour and stir until combined. You should have a slightly tacky but moldable mixture. Add more rice flour as needed if too wet to handle.
Form into thin (roughly 1/4-inch-thick) patties the size of the palm of your hand (we used ~1/4 cup of sweet potato mixture per patty). In the meantime, wipe down and heat the large rimmed skillet you used to sauté your vegetables, or another one (we prefer cast iron or non-stick).
Once hot, add a little avocado oil to lightly coat the bottom of the pan (we used ~1/2 Tbsp // use more for a crispier effect). Add enough fritters to comfortably fit without crowding. Pan fry until golden brown — ~3-4 minutes on each side.
Optional: For even crispier fritters, continue baking in a 400 degree F (204 C) oven for 10-15 minutes.
Serve hot topped with mint chutney (optional). Best when fresh. Store leftovers covered in the refrigerator up to 3-4 days, or in the freezer up to 1 month. Reheat on the stovetop over medium heat, in a 350 degree F (176 C) oven, or in the microwave until hot. If frozen, thaw slightly before reheating.
*Nutrition information is a rough estimate calculated with 2 Tbsp (30 ml) avocado oil and without optional chutney.