In a large saucepan, add 100ml red lentils and enough water to cover them by about 2-3cm. Bring to a boil over medium-high heat, then reduce to medium and simmer for 30 minutes. Stir frequently and add more water as needed during cooking as the lentils absorb it. When done, the lentils should be yellowish and very puree-like but still slightly thicker than smooth purée.
While the lentils cook, finely chop 2 onions. Heat 5 tablespoons olive oil in a large pan over medium heat, add the onions, and cook for 8-10 minutes until soft and caramelized, stirring occasionally. Finely chop 4 spring onions and parsley (about 2 handfuls) and set aside.
In a small bowl, mix 2 tablespoons tomato paste, 2 tablespoons paprika powder, 1 teaspoon black pepper, 3 teaspoons salt, 1 pinch coriander powder, and 1 tablespoon mint.
When the lentils are ready, stir in 200ml bulgur and mix very well. Cover the saucepan and let rest for 15 minutes.
Add the spice mixture to the lentil-bulgur mass and knead thoroughly (wearing disposable gloves is recommended to avoid staining your hands with the tomato paste). Work in the caramelized onions, spring onions, and parsley until the mixture is completely uniform.
Shape the mixture into small patties, arrange on lettuce leaves, and squeeze lemon juice over just before serving.