How to make really good soup from nothing (and a $2.50 bunch of cavolo nero)

Today's Three Ways With... column is all about food waste - using up the stuff you'd normally throw away. While I was thinking about it, I realised I do a lot of food 'saving' that's unconscious. Things aren't so desperate that I reuse teabags (I remember seeing a posh and terrifying friend of my mother's doing this and being thoroughly shocked), but I do like to extract maximum value from things.

Leftovers get taken for work lunches, baguette ends are turned into breadcrumbs or crostini, spotty bananas are frozen for smoothies or baking - it's stuff that seems basic household common sense. But I fear that the very existence of campaigns like Love Food Hate Waste (which I'm proud to support) means that people have lost their way.

I guess if you don't cook often, or see cooking as a difficult chore, then you're less likely to think about using up your leftovers. Or, you may be like someone I know who cooks a lot, but over-caters massively and then just chucks stuff in the bin (a long-lost Presbytarian gene means I am morally outraged by this). But it's not that hard.

If you want to waste less, you need to be mindful right from the start. You need to plan meals to a certain extent, you need to shop with purpose and cook with efficiency. That means, when you get excited by seeing huge bunches of cavolo nero at the shops for $2.50, you need to think on your feet about what you're going to do with it. In this case, I let it sit in the fridge for a few days, waiting for inspiration to strike. We have a small, ill-designed fridge and it's fundamentally unsuited to having lots of stuff in it. So, when I realised the cavolo nero was balanced on Sunday night's leftover roast chicken, something stirred in my brain.

The chicken, stripped of fat and skin, went in the pot, with an onion, a carrot and some limp celery. I covered it with water and an hour or so later, I had a vat of delicious stock. I sauted the rest of the celery, another onion and some garlic in a bit of oil leftover from a jar of sundried tomatoes, added a bowl of cooked quinoa from the fridge, a kumara from the cupboard and the cavolo nero. The stock went in, along with some herbs from the garden and before long 'nothing' had turned into soup. We ate half of it on the spot, and the rest went in the freezer. Not complicated, not costly, not wasteful. Why is this stuff dressed up to be difficult?

What's your favourite way to combat food waste?