Cook the pasta in plenty of salted boiling water according to the packet instructions. Add the frozen peas for the last 2 minutes of cooking time.
Before draining, scoop out a mugful of the pasta cooking water and set it aside.
Heat the olive oil in a large pan over low heat. Add the minced garlic and cook for 1 minute - do not let it brown.
Add the drained pasta and peas to the garlic oil. Toss well.
Add the lemon zest, lemon juice, oregano and a splash of the reserved pasta water. Toss again until the pasta is coated in a light sauce.
Serve topped with grated parmesan and plenty of black pepper.