Poke 1 sweet potato a few times with a fork. Microwave until very soft, about 5–7 minutes or until fork tender. Cut it open and scoop the soft inside into a large bowl.
Add 1 can lentils (rinsed - shake water off well) to the bowl. Mash with a fork until mostly smooth. Small lumps are okay.
Add ½ cup all-purpose flour, 1 cup crumbled feta, 1 large egg, ½ red onion, 1 clove garlic, 1 teaspoon dried oregano, ½ teaspoon ground cumin, ½ teaspoon salt, and black pepper. Mix well. The mixture should be thick and easy to scoop. If it feels too wet, add a little more flour.
Heat a little olive oil in a pan over medium heat. Scoop about 2 tablespoons of mixture, flatten gently, and cook 3–4 minutes per side until golden.
Serve warm with tzatziki, yogurt, or a squeeze of lemon. Enjoy!
