Heat 1 tablespoon oil in a large skillet over medium high heat. Add onion and cook until soft and translucent, 3 minutes. Add mushrooms and 1 tablespoon olive and cook until mushrooms are golden brown, 7 minutes. Add garlic and cook until fragrant, 1 minute. Remove from heat and wipe out skillet.
In the bowl of a food processor, add mushroom mixture, lentils, oats, eggs, smoked paprika and salt. Process until the mixture is fully incorporated and starts to ball. Roll into golf ball sized spheres and press down slightly to make a cake-like patty.
Make the yogurt sauce by combining all ingredients in a medium bowl, and season to taste.
Line a baking sheet with paper towels. Heat remaining 2 tablespoons olive oil in wiped skillet over medium high heat. Add patties, working in batches, and cook until golden brown, 3 minutes per side. Transfer to prepared baking sheet. Serve with yogurt sauce immediately.
Video
Notes
Storage: These lentil cakes will keep in an airtight container for 3 to 4 days in the fridge.