In a medium saucepan, combine red lentils with water. Bring to a boil and cook for 10-12 minutes until soft. Drain and cool.

In a large mixing bowl, combine the cooled lentils with grated sweet potato, chopped onion, and minced garlic. Add spices, salt, pepper, and cilantro, then mix in the flour.

Allow the mixture to rest for 5-10 minutes at room temperature.

Heat a skillet over medium heat with olive oil.

Shape the mixture into patties and fry in the skillet for 3-4 minutes on each side until golden brown.

In a blender, combine avocado, garlic, cilantro, lime juice, and yogurt. Blend until smooth.

Arrange patties on a serving platter and drizzle the sauce over them, or serve it on the side.