Wash the red lentils in a wire mesh strainer and rinse them well and set aside. Put 3 tbsp of butter in a saucepan and melt it. After that add the onions and garlic and saute them 3 minutes. After the onions get softy, add the white flour and saute them about 2 minutes.
Add the potatoes, carrots, red lentils, salt and black pepper to the saucepan and then pour the 8 cups of water on to the mix. Stir the mix 5 minutes at medium heat and then close the lid and bring to boil.
Simmer for 20 minutes until the lentils and vegetables are tender. Then insert a hand blender into the saucepan to puree the mix to reach the consistency of you want. And then transfer the soup into a soup bowl.
Meanwhile, in a nonstick skillet melt the 2 tbsp butter and add the red paprika powder and red paprika and cook for 1 minute.
Ladle the soup into small soup bowls and sprinkle some of the topping sauce mixture into each one. Serve with wedge cut lemon.