Boil the potatoes, peel them and let them cool down a little. Press through a potato press or pound very finely. Now gradually knead in the flour and egg yolk.
Quarter the dough and form 1 cm thick rolls from each quarter. Cut with a knife into 2 - 3 cm long pieces and let simmer in boiling salted water. When you swim up you are done.
I used a hand blender for the pesto. First grate the cheese and set aside. In a tall container, puree the herbs and oil with a stick.
Gradually add the nuts and cheese, possibly also oil. Finally, season to taste with salt, pepper and lemon juice.
Tip:
I always make the pesto out of hand. Everything I have there goes in. You can also use spinach and garlic.