What's the healthiest way to prepare broccoli?

• 22 brilliant broccoli recipes

What is the healthiest way to prepare broccoli? N. Leaver

When I was working in television I remember asking an editor to remove the on-air chef's line, "Eat a brassica a day and you can drink and smoke as much as you like and you will never die". The drivel food celebrities expound. Brassicas are vegies in the cabbage family – kale, brussels sprouts and turnips, to mention a few. Studies have shown that people who have a diet high in brassicas are less likely to develop certain cancers. There is a compound in brassicas called glucosinolates that appears to be doing the work. It sits dormant in the leaves and stem but when chewed by bugs it's transformed by an enzyme, making the leaves less palatable to the insects. We, however, find these mustard-tasting compounds rather delicious. To get the best out of your brassicas, you need to eat them raw to get the chemical reaction going. Steaming for a short period will not affect the enzyme or the vitamin C content. Microwaving brassicas until cooked destroys vitamin C and deactivates the enzyme. Boiling leaches the glucosinolates into the water. So, if optimum health benefit is your goal, serve broccoli raw, lightly steamed or flashed briefly in a hot pan. Remember that however you prepare them, brassicas are still full of fibre and are incredibly tasty. Bacon, butter and lemon juice are their natural companions.

My sweet potatoes are not sweet. They are mealy. A.Hirst

Have you ever eaten a raw sweet potato? It is nasty and starchy. Not sweet. That starch is a polysaccharide – which literally means "many sugars", in this case glucose molecules lined up to make the starch. When they are connected like that they don't taste sweet. There is an enzyme that breaks the starch molecules apart into glucose molecules. It is active between 58 and 77 degrees. If you put you sweet potatoes straight into a hot oven, they are not going to spend much time in the temperature zone in which they sweeten up. You can sous-vide sweet potatoes within this temperature zone orpeel and chop them and drop the chunks into a large pot of water around 80 degrees. Cover and leave in a warm spot for an hour. Drain, dry, lightly oil and season and roast as usual. The now sweet juice will brown and caramelise as it cooks, creating all sorts of new flavour compounds.

How do I make salads delicious like they do in restaurants? L. Ho

Use glutamic acid. The real MSG – umami-rich ingredients such as parmesan, pecorino and anchovies. Take 180ml of extra virgin olive oil, 30ml of dijon mustard and 30ml of really good wine vinegar, add four anchovy fillets or two packed tablespoons of grated parmesan or good pecorino and blitz in a food processor or with a stick blender. Dress the salad at the table by pouring as much as you like into the bowl, adding the leaves then massaging the dressing through.

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