Boil the spaghetti according to the instructions on the package. Heat 4 tablespoons olive oil over a medium flame and sauté the leek for 8-10 min, until smooth. Add the salt and pepper. Cut the avgotaraho in thin, transparent slices and mix with the lemon juice and 4 tablespoons olive oil. Strain the spaghetti, add the leek, stir, add the avgotaraho and mix. Sprinkle the lemon zest and a generous amount of pepper. Serve immediately.