There’s an unusual perennial vegetable lurking unsuspected in many gardens at this time of year: rhubarb flowers. You should remove the flower stems from rhubarb to stop it wasting its energy on seed production in any case, so instead of chucking it on the compost, you could use it, as they do in the far east, as an exotic seasonal ingredient.

The secret to preparing rhubarb flowers is to know that the tiny individual flowers that make up the head do not contain any oxalic acid, the substance that makes rhubarb so sour, but the flower stem does. The stem is a branching structure that goes right inside the head so you’ll never get it all out, but if you just cut off the most accessible bits you’ll have got rid of most of it. Also be sure to remove the stem leaves, which are presumably as poisonous as the basal ones, and the papery bract which surrounds the flower head.

The result is still sour, but interestingly rather than overpoweringly so. It goes best in dishes where there is a sour element and you can often leave out vinegar or lemon juice from a recipe in compensation. I find it delicious boiled for four or five minutes with broccoli sprouts, then drained and served with oil and salt over the top, leaving out the shake of lemon juice that I would usually add. It also goes very well in a stir fry.

Since a flower head will contain some stem and therefore some oxalic acid no matter how carefully you prepare it, it would be a bad idea to consume excessive amounts of them. This is also true of the rhubarb stems that are more normally eaten.

More on rhubarb in Rhubarb and elderflower jam, and a surprise.