Combine lentils and water in a saucepan; bring to a boil, then simmer for 15 minutes until soft. Drain thoroughly to remove excess moisture.

Steam or boil sweet potato cubes for 12 minutes until tender; mash in a large bowl.

Add the cooked lentils, breadcrumbs, egg, cumin, paprika, cayenne, and salt to the mashed potatoes; stir until a cohesive dough forms.

Form the mixture into 8 equal patties.

Heat olive oil in a non-stick skillet over medium heat and fry the patties for 4-5 minutes per side until crispy and golden.

In a food processor, blend the avocado, yogurt, cilantro, lime juice, and garlic until smooth.

Serve the patties warm with the creamy sauce drizzled over the top.