Cook the tortellini in salted water according to the instructions on the packet, drain into a sieve and drain.
Wash the asparagus, peel the lower third and cut the stalks into bite-sized pieces. Peel the garlic and dice very finely. Clean and wash the spring onions and cut into rings.
Heat the oil and butter in a pan, fry the asparagus for about three to four minutes at a medium temperature. Add the garlic and spring onions, cook for another minute or two. Stir in the crumbled feta and parmesan, add a spoonful of vegetable stock, let the cheese melt.
Fold in the tortellini, lemon zest and parsley and season with a little lemon juice, pepper and possibly salt.