In a medium saucepan, combine 1 cup of red lentils with 2 cups of water. Bring to a boil and then reduce the heat to a gentle simmer, allowing the lentils to cook for 10-12 minutes until they are soft but not mushy. Drain any excess water and let them cool slightly while preparing the next steps.

In a large mixing bowl, add the cooked lentils along with grated sweet potato, finely chopped onion, minced garlic, cumin, paprika, ground coriander, salt, pepper, and chopped cilantro. Stir until the mixture holds together well and let it sit for 5-10 minutes to improve binding.

Heat about 2 tablespoons of olive oil in a skillet over medium heat. While the oil heats, shape the lentil and sweet potato mixture into palm-sized patties, ensuring they are compact and even in thickness for uniform cooking.

Once the oil is shimmering, gently place the patties into the skillet, making sure not to overcrowd the pan. Cook each patty for 3-4 minutes on one side until golden brown, then carefully flip and continue cooking for another 3-4 minutes.

In a blender, combine 1 ripe avocado, a handful of chopped cilantro, minced garlic, lime juice, and plain yogurt. Blend until smooth, adjusting the consistency with water as needed.

Once cooked, remove the patties from the skillet and place them on a paper towel to absorb any excess oil. Serve the crispy sweet potato and red lentil patties warm, drizzling the creamy avocado sauce generously over them or presenting the sauce on the side for dipping.