Cut the onion in half, peel it and then cut it into a 2-3mm (⅛") dice.
Slice the wild garlic leaves into 1cm (½") strips and chop the stems as finely as you can. Keep the leaves and stems separate.
Prepare the asparagus by snapping off the woody section and discarding. Cut the remaining asparagus into 1cm (½") sections, leaving the tips a little longer.
Heat the olive oil in a 28cm or 11" deep frying pan over a low/medium heat. Add the anchovy fillets, onion and wild garlic stems, then cook for 2-3 minutes, stirring continuously.
Add in the wine, vegetable stock, passata and the salt and pepper, make sure you taste to get the salt right. Then cover with a lid and cook for 10 minutes.
Add the pasta, return the lid, turn the heat up to medium and cook for 2 minutes less than it says on the packet.
Have a taste of the pasta here; it should be undercooked, but it should have 2-3 minutes left until it is perfect. Stir in the asparagus and cook for 2 minutes uncovered.
Check the pasta is cooked to your liking, then stir in the wild garlic leaves, cooking them for no more than 30 seconds.