Mix the balsamic vinegar with the mustard and oil, then season with a little salt and pepper.

Rinse the quinoa in a sieve under running water, then cook in boiling salted water for 10–15 minutes until tender. Drain, leave to cool.

Trim the ends off the asparagus and, if necessary, peel the lower third. Cut the asparagus into 5 mm pieces. Leave the asparagus tips whole. Cook the asparagus pieces in boiling salted water for 3–4 minutes; add the asparagus tips for the last minute, then briefly plunge everything into a bowl of ice-cold water.

Finely chop the parsley and spinach.

Place the quinoa, asparagus, parsley and spinach in a bowl and stir in the sauce. Leave the salad to stand for 40 minutes before serving.