Cook the sweet potatoes in boiling water for about 15 minutes until tender. Drain and mash, leaving a few lumps for texture.
In a saucepan, combine the lentils and 2 cups of water. Bring to a boil, then reduce heat and simmer for 15 to 20 minutes until soft. Drain excess water.
In a mixing bowl, combine the mashed sweet potatoes, cooked lentils, onion, garlic, cumin, paprika, salt, and pepper. Mix well.
Shape the mixture into patties, about golf ball to small burger size.
Heat oil in a frying pan over medium heat and fry the patties until golden brown on both sides, about 3 to 4 minutes per side.
For the sauce, blend avocado, cilantro, lime juice, and salt until smooth. Add water if needed for a thinner consistency.
Serve warm with the avocado cilantro sauce.
Notes
Fry in batches for optimal crispiness. Adjust seasoning to your taste.