Pistou is a Provençal basil pesto that’s made without pine nuts, and my zero-waste version replaces the basil with radish leaves. It makes an aromatic, brilliant-green sauce for grilled vegetables, fish and meat, or as a topping for stews and soups, as I’ve done here. For today’s recipe, I wanted to cook from root to fruit, using both the radishes and the leaves in the same dish, but both also stand alone.
Radishes, and especially their leaves, are often sandy, so soak the whole bunch in a large bowl or sink of cold water for five minutes, and shake the bunch under water to loosen any dirt and ensure the water gets into the middle. Scrub off any visible soil, then run under the tap and leave to drain for five minutes before preparing.
Chilled radish soup with radish leaf pistou
Chilled soup is a seasonal treat for when summer is at its hottest. Using red and/or purple radishes gives this soup a pastel-pink hue that’s especially striking against the vibrant green pistou.
Traditionally, pistou is made with a pestle and mortar, resulting in a more textural sauce; if you want to try doing it the old way, finely chop the leaves and garlic before pounding them in the mortar with the grated gouda. Once they’ve broken down into a paste, stir in the extra-virgin olive oil a bit at a time until it’s a consistency you like.
If you don’t have any stale bread to hand, you can also thicken the soup with 50g chopped walnuts. The bread gives the soup a smoother texture, though, even if you use wholemeal sourdough as I did, but the walnuts add a additional depth of flavour. And while you’re making the final adjustments to the seasoning, add more vinegar and/or oil to taste.
For the pistou
The leaves from 1 bunch radishes (about 50g), washed and drained
1 small garlic clove, peeled
30g gouda, grated (optional)
6-8 tbsp extra-virgin olive oil
Salt and black pepper
For the soup
1 bunch red or purple radishes (about 200g), plus a few sliced radishes, to serve
300ml buttermilk, or live yoghurt or a plant-based alternative
1 slice day-old bread (about 80g), or 50g chopped walnuts
1 small garlic clove
1-2 tbsp extra-virgin olive oil
2-3 tsp red-wine or sherry vinegar
First make the pistou. Roughly chop the radish leaves, then blend them with the garlic, gouda, if using, and extra-virgin olive oil to make a thick paste. Season, then store in a jar in the fridge for up to a week.
For the soup, blend the radishes, buttermilk, bread (or walnuts) and garlic, then stir in the extra-virgin olive oil and vinegar, to taste. Season generously, then chill for at least an hour. Season again, adding more vinegar and/or oil, to taste, then ladle into bowls and serve topped with a spoonful of pistou and a few sliced radishes.
