DIY Pantry

How to make pesto: easy hacks to use up leftover herbs

2nd July 2018

How many times have you bought a bunch of herbs only to leave most of it to wilt in the back of the fridge. Food writer, Malou Herkes, shares her easy hacks to use up leftover herbs, from pesto to herb butter.

Leftover herbs

Fresh herbs are all too easily wasted. Often because we fail to store them properly or we forget they’re there altogether. It’s a shame because herbs can add so much to our cooking: a diversity of flavour and freshness that brightens a plain last-minute dinner into something vibrant and exciting. Thankfully, herbs are easy to incorporate into our cooking when we know how. Here are some ideas.

How do you store fresh herbs?

With the exception of basil which wilts depressingly fast, fresh herbs are best stored in the fridge, wrapped in slightly damp kitchen paper or cloth. I also find soft herbs, like parsley and coriander, keep just as well in a glass with a little water in the bottom (like you would treat flowers). Basil is best kept out of the fridge, but use it up fast. It doesn’t last long!

How do you preserve fresh herbs?

infused oil

Photo: Natalé Towell.

If you know you won’t use your herbs in time, herb-infused olive oil is a wonderful (and quick) way to make the most of their flavour for weeks to come. Steep sage in olive oil, then strain it out and bottle – my new favourite thing on fried eggs.

Frozen herb butters, too, transform wilting herbs into time capsules of flavour. Roughly chop whatever herbs you have (finely chop and add the stalks of soft herbs, but discard woody stems), then combine with softened butter. Add surplus chillies, garlic or even ginger, if you like, then wrap in greaseproof paper into a cylinder shape and place in the freezer. After 30 minutes, take it out, slice into rounds and return it to the freezer. Use it in your cooking straight from frozen, melted into risotto, thrown in with fish as it cooks, or for finishing off a barbecued steak.

Alternatively, blitz or chop up herbs, place into ice cube trays, pour in olive oil and freeze. Once set, pop them out and place into sandwich bags. Use them instead of olive oil during cooking.

Herby green sauces: from chimichurri to gremolata

green sauce

Pan-fried mackerel with green sorrel sauce

Perhaps my favourite way to use a sad bunch of herbs is to chop or pound them into a loose dressing, to liven up eggs, tender new potatoes, a basic bowl of rice, roasted vegetables, grilled meat or fish. You might have heard of chimichurri – a spicy green sauce hailing from Argentina, and often served on steak. Or zesty Italian gremolata – a green herb garnish with lemon, garlic, parsley and anchovy, traditionally used to finish the traditional Milanese dish, osso bucco, but which now adorns dishes from pasta to fish.

The premise of these so-called sauces is simple: chop whatever herbs you have with something piquant and punchy (kitchen staples like anchovies, capers, gherkins, mustard or vinegar come to mind), add a bit of citrus for brightness and perhaps oil to loosen it, and you’ve got the starters for a tasty meal. Leftovers can be stored in the fridge for a good couple of days providing it’s covered in a layer of oil.

And then there’s pesto


From the Italian verb ‘pestare’ – to pound or crush – pesto traditionally consists of basil, garlic, Parmesan, pine nuts, olive oil and lemon juice, bashed together into a paste in a pestle and mortar (hence the name). Originally from Genova, pesto has become a popular export. Most commonly eaten with pasta, it has the nutty-umami power to elevate an omelette, a tray of roasted veg or a drab sandwich with little effort.

While purists might disagree, pesto is the winning formula to use up all sorts of herbs or green leaves. Especially ones you’ve got wilting in the fridge. Basil is delicious in pesto, of course, but there’s also coriander, mint, parsley, rocket, sorrel or tarragon. Note that this works best with soft herbs – woody ones like rosemary and thyme, less so. I’ve found you can use the ratios given below with peas or blanched green leaves, like chard or beet tops, too. Or swap the pine nuts for any nuts you might have in the cupboard. It might not be the traditional pesto you’re used to, but it’ll taste good nevertheless.

How to make leftover-herb pesto in 4 easy steps

Step 1

Pesto herbs

Peel ½ a clove garlic, then pound to a paste in a pestle and mortar with a pinch of sea salt. Alternatively, chop with a knife. Pick and roughly chop 1 large bunch of leftover herbs, then bash – along with the garlic – to a paste in the mortar or pulse in your blender.

Step 2

Add 1 handful of pine nuts, then pound or blitz again. Stir in half a handful of freshly grated Parmesan.

Step 3

Stir in just enough olive oil to bind the pesto into an oozy consistency, then stir in another half a handful of Parmesan.

Step 4


Season to taste with salt and pepper. Keep tasting, adjusting with a little more grated Parmesan and lemon juice if you think it needs it. Serve immediately or store in the fridge covered in a film of olive oil for several days.

From mouldy cheese to stale bread, keep your food from going to waste with these top tips.

For more DIY pantry ideas, check out Malou’s guides to DIY dairy-free milks and homemade almond milk as well as how to preserve lemons, infuse olive oil, make apple cider vinegar, an easy mayonnaise, gut-friendly kombucha, a traditional buttercreamy yoghurt, hummus and icing sugar.

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