Add lentils to a saucepan with 2 cups of water. Bring to a boil, then reduce heat and simmer until tender and water is absorbed, about 10-12 minutes. Let cool.
Steam or boil sweet potato cubes until very soft, about 10-15 minutes. Drain and mash.
In a large bowl, combine cooked lentils, mashed sweet potatoes, red onion, garlic, parsley, oats, cumin, paprika, salt, and pepper. Mix well.
Let the mixture sit for 10-15 minutes so the oats absorb moisture. If the mixture is too wet, add a bit more oats.
Form into small patties using your hands.
Heat a little olive oil in a nonstick skillet over medium heat. Cook patties for 3-4 minutes on each side until golden and firm.
For the tahini dressing, whisk together tahini, lemon juice, maple syrup, mustard, and garlic in a bowl. Add water gradually to reach desired consistency. Season with salt to taste.
Serve patties warm with the tangy tahini dressing drizzled over top or on the side.