In a blender add tomatoes, walnut and parsley and blend it to a puree.

In a pressure cooker heat up olive oil. Add chopped garlic and chilli flakes. Fry it for some time.

Add sausages and bell pepper and then saute for some time. To that add the puree mix.

Once everything is mixed add the pasta. Kindly note that you don't have to boil the pasta before.

Mix everything well. Add water if required. Add water upto the pasta.

Close the pressure cooker lid and cook the pasta upto 2 whistles. Let the steam release by itself. Open the lid and add oregano. Serve it with garlic bread or cheese bread.