Remove the sausages from the casing and divide into 3 parts. Peel the onion, rinse and cut into small cubes. To serve, rinse and dry the lettuce leaves; Wash the parsley and separate the leaves from the stems, grate the cheese on a fine grater.
Fry the onions. Heat the vegetable oil in a frying pan, add the onion and fry, stirring, until transparent. Then remove the pan from the heat.
Boil sausages with spaghetti. Poke a few pieces of spaghetti all the way through each part of the sausage, being careful not to break the spaghetti. Repeat this with all the sausages. Place a saucepan with plenty of water on the fire. Carefully place the spaghetti and sausages into the boiling water. When the spaghetti sinks to the bottom, add salt and cook until the pasta is half cooked, about 3 minutes. Drain the water.
Stew noodles with onions in tomato sauce. Place spaghetti with sausages in the pan with the fried onions and turn on medium heat. Add ground black pepper, paprika and tomato paste. Stir everything, cover with a lid and simmer over low heat for about 3-5 minutes.
Place the spaghetti on a plate with lettuce leaves, garnish with parsley leaves, and place a bowl of grated cheese next to it.