In 2009 I teamed up with Penguin and specifically the amazing Lantern Books to create The Thrifty Kitchen, which I co-authored with my mother Suzanne. The book offered recipes that were no waste, and which used the "lesser" cuts of meat - think mince and pork belly. Back then pork belly was as cheap as anything,  even though it's now up there in price with beef fillet! But we worked to use leftovers as well.

What interests me now, though, is the unbelievable wastage of the food we've already bought. What are we to do with the half bunch of parsley, the quarter onion, the deflated celery from last night's dinner. I say these ingredients can be reinvigorated into something entirely new. My recipes work to use the whole portion of something, so you can use all of what you buy. Or I seek to use those fridge leftovers that will be in the bin by Tuesday if we don't cook them now. This recipe is the pesto I make to use up leftover greens in the crisper. You can use lettuce or spinach, rocket, herbs, even a stalk of broccolini or two. The only premise? It has to be green. Have fun with my favourite fridge forage pesto!

A lovely charred cos lettuce is a gorgeous accompaniment to the green feast. Just drizzle with olive oil and salt, char on a hot grill, and squeeze over lemon to serve. 

Fridge forage pesto recipe

• 1 brown onion, peeled and cut into 8 through root end
• 8-10 cups torn mixed leaves and tender herbs (such as lettuce, rocket, silverbeet, coriander, parsley)
• 1 head garlic, about 1cm cut from top
• 2-3 tsp extra virgin olive oil, plus extra
• ¼ cup sesame seeds, plus extra to serve

• ½ cup grated ricotta salata (salted dry ricotta) or crumbled ricotta
• grated zest of 1 lemon
• 400g textured pasta (such as fusilli, pici or mafaldine)

Blanch onion and mixed greens and herbs in a large pot of boiling salted water until tender, about 3 minutes. Using tongs, transfer greens to a bowl of iced water to shock. Drain and squeeze excess water from greens. Reserve water in pot.

To roast garlic (do extras if you want to use them up, for a later time), preheat oven to 200C. Place garlic in small baking tray and drizzle 2 teaspoons olive oil over each exposed head. Cover with foil and roast 30-40 minutes, until very soft.

In a food processor, process sesame seeds then add onion and green mixture, half the ricotta and squeeze out garlic from one head. Pulse to form a paste. With motor running, add 3 tablespoons olive oil, then add 3 tablespoons water to create a smooth paste (it will be quite watery).

Heat water from blanched greens and cook pasta to packet instructions, draining it in the last 5 minutes before al dente (it will cook more in a moment).

Meanwhile, heat the pesto in a saucepan or deep frying pan. I use this Le Creuset small casserole (see below) so I can serve the pasta at the table in the pot. Add the undercooked pasta to the sauce and cook, tossing well. The pasta will absorb the excess water as it cooks to al dente. Divide pasta between bowls or take it to the table in the pot. Scatter over remaining ricotta (which I forgot to do for the picture!), citrus and sesame seeds and drizzle with oil.