Wash the leeks and slice them in half lengthwise, then cut across into 1 cm slices. Heat the olive oil over medium-high heat in a large skillet. Add the leeks and a teaspoon of salt, and cook, stirring, for 5 minutes or so until the leeks have softened slightly.

Remove the sausages from their casings and add to the leeks. Break up the sausage with a wooden spoon or a potato masher until there are no large chunks left. Continue cooking for 7-10 minutes, until the sausage is cooked and brown bits start to form on the bottom of the pan.

While the sausage is cooking, it's time to start thinking about pasta. Bring 2 litres of water to a boil in a medium-large pot, and add 1 Tablespoon of salt. Cook the pasta according to the package instructions.

Add the tomato paste, garlic powder, and dried oregano to the sausage and leek mixture and stir to combine. 

It should be about time to drain the pasta, being sure to save a good amount of pasta cooking water to adjust the sauce with. 

Reduce the heat, add the sour cream to the sausage and leek sauce mixture, and add a good splash of the pasta water to form a creamy sauce. Then add the pasta to the pan, and stir everything together keeping the pan on low heat until the pasta is coated with all that good stuff. Use additional pasta water to loosen up the sauce as needed.