Tie the asparagus spears in bundles of five, heads together, securing each bundle under the tips and near the base with string.

Cook the asparagus in an asparagus steamer if you have one, or wedge the bundles upright in a deep saucepan and add enough boiling water to come three-quarters of the way up the stems.

Cover the tips with a cap of kitchen foil and simmer gently for 5-10 minutes, until tender.

Meanwhile, whisk together the mustard, vinegar, oil, salt and chilli powder.

Drain the asparagus and untie the bundles. Place on a warmed serving plate and pour over the mustard sauce. Serve at once.