Eva Cross, St. Clair College Culinary Management Faculty, says the answer is pretty simple.
Bring a pot of generously salted water to a boil then cook them without a lid until just tender. The salt will bring out the flavour and boiling the veggies uncovered is crucial to keeping their colour.
"Green vegetables contain enzymes that if covered while boiling turn their colour brownish or oxidize," says Cross. "The enzyme will be released in the steam. If you cover the pot with a lid, the enzyme will be forced back into the water, and this ruins the colour of the vegetable."
This method works for green vegetables such as broccoli, asparagus, green beans and Brussels sprouts, says Cross.
Preparing these green veggies ahead of time? No problem, says Cross, offering a trick of the trade:
After boiling, just plunge them in a bowl of ice-cold water (called blanching) and store in the refrigerator.
"When it's time to serve, finish them with a little butter and salt and pepper and pop them in the microwave for 2-3 minutes until hot," says Cross. "They will be as green as if you just cooked them."
If you do not have a microwave, Cross says to plunge them back into a pot of boiling water to heat through for about 30 seconds, drain, dress and serve.
"This is the method that restaurants use to get that perfect green vegetable on your plate," explains Cross.
So say goodbye to discoloured and unappetizing greens and start cooking with colour in mind!