Discard the woody ends of the asparagus. Cut off the tips and set these aside.
Cook the pasta according to the packet’s instructions. Add the asparagus tips to the last minute of the cooking, then drain and keep warm.
Meanwhile, finely chop the spring onion and garlic. Cut the asparagus stems into small pieces.
Heat the oil in a pan, add the spring onion and garlic. Fry for 30 seconds, then add the peas and asparagus. Add the lemon juice and a dash of water. Sautee, under cover, for 3-5 minutes until tender.
Let it cool a bit, then transfer the mixture to a small food processor. Add the mint and pine nuts, then whiz until you get a textured paste. Season to taste, add some lemon juice and olive oil to your liking.