Roast The Sweet Potato: Preheat the oven to 425 degrees F. Poke holes in the sweet potato with a fork, then roast it for 1 hour, until it is soft when pierced. Remove from the oven, scoop out the flesh, and let it cool.
Cook The Rice: Cook the brown rice according to package instructions. Set it aside to cool before using.
Make The Flavor Base: In the bowl of a food processor, combine the scallions, garlic, lemon juice, salt, paprika, and cumin. Pulse until the mixture forms a smooth paste.
Combine The Burger Mixture: Add the roasted sweet potato, cooked rice, and chickpeas to the food processor. Pulse a few times, until the ingredients are combined but still have some texture.
Mix The Ingredients: Transfer the mixture to a large bowl. Add the panko breadcrumbs, feta, and parsley, then stir until everything is evenly incorporated.
Form The Patties: Shape the mixture into 8 equal patties, pressing them firmly so they hold together.
Cook The Patties: Heat 1 tablespoon of olive oil in a skillet over medium heat. Add the patties and cook for 4 to 5 minutes, until golden brown. Flip the patties and cook for another 4 to 5 minutes, until the second side is golden and heated through. Cook in batches as needed, adding more olive oil to the skillet.
Serve: Serve the burgers warm as a main dish with a salad, or place them on a bun with mayo, lettuce, and red onion for a more traditional burger experience.