Cook the pasta according to the package instructions, then drain and keep warm.
Meanwhile blanch the peas and asparagus (or steam over boiling water). This will take about 3-5 minutes.
Dry-fry the pine nuts in a frying pan and set aside.
Chop the onion. Heat 1 tbsp oil in the frying pan, cook the onion until soft. Add the lemon zest and juice, mustard and Greek yogurt.
Drain the vegetables, add to the sauce together with the pasta.
Warm through for a minute, season to taste, then serve with the with pine nuts scattered on top.