Until I looked it up, I wasn't aware the rosella I bought over the weekend at the Wan Chai wet market is also known as wild hibiscus (Hibiscus sabdariffa).
Although I was familiar with its taste, I had never seen wild hibiscus 'live' - only as dried flowers or infused in syrup. When I was preparing the flowers, I started to suspect they were the same thing. The bright pink juice that dripped from the petals after I'd rinsed them looked very similar to the colour of refreshing hibiscus drinks I've tasted in Mexican and Middle Eastern restaurants.
Rosella has magenta petals surrounding a hard, pale green bud. When buying it, look for firm petals that snap crisply when pulled from the bud, which should be firm and not mouldy. Buy more than you think you'll need because the actual yield is quite small: I bought 2kg and ended up with about 650 grams of petals.
The flowers, which have a distinctive fruity, acidic flavour, are delicious and beautifully coloured when steeped in hot water. This rosella 'tea' is usually made with dried flowers, but can also be made with fresh ones. Rosella is in season now, and will be available for a few more weeks. To dry them for future use, snap off the petals as close as possible to the stem, rinse with cold water then lay out on screens for a few days, turning them so they dry evenly. It's easier and faster if you use a dehydrator.
They can also be made into rosella jam. Separate the petals from the buds. Put the buds in a pan and add twice the amount of water (by weight). Bring to the boil then lower the heat and simmer for about an hour (this extracts the pectin from the buds). Strain the liquid into a clean pan and discard the buds. Weigh the rosella petals and add an equal weight of sugar. Put the petals and sugar into the pan and bring to the boil, stirring frequently. Cook, stirring often, until the jam reaches the setting point. Stir in some fresh lemon juice then ladle the jam into sterilised preserving jars. Cover with sterilised lids and process for 15 minutes in a boiling water bath (or simply store in the fridge).