When cooking, I only cook up enough for that meal. I have a small slow-cooker which will hold just enough stew for two people, so no left overs. If there are left overs, it means we cooked too much. Stews can be started off in the slow-cooker then transferred the haybox, minimising power waste too.
But I do also cook up batches of things like rice or beans. The rice is kept in the fridge and will keep for up to a week and is good for making quick meals, especially this time of year when we turn it into rice salad so there's no extra heat put into the house that we don't want. Beans I will spread on a silicone sheet and freeze down then pack into a bag so we can grab just what we need when we need it. I usually have two bags of different sorts of beans in the freezer. When one runs out, I cook up a different sort of bean.
Bread is bought from the Too-Good-To-Go app at €3 a box for yesterday's bread, though for some reason there is usually at least some of that morning's bread too. We feast on the best looking bit and the rest goes in the freezer. When the supply starts to get low, we book another box to pick up the next time one of us goes to town. My other half is in town right now and has just picked this box up.
This reduces food waste even before it hits our home as it's being removed from the waste stream. Mystery fresh bread from that morning notwithstanding. I have no explanation for that...
Then we have also managed to source two butchers that will give customers free offcuts. Last Friday the boys went shopping at a town a little further away as there was something they needed that they couldn't get in the nearest one and my other half went into the big butcher place and bought a chicken, a pork heart and two pork tongues and asked about offcuts. The guy asked how much he wanted so he hopefully suggested 2kg and received this bag which weighed over 3kg.
I sorted out anything with bones and froze them to turn into bone broth. That left over 2kg of fatty offcuts with skin, mostly pork, which I rendered down to get lard from. I got this much...
Then the left-overs, which were rich in meat, fat and collagen, I cut up into small pieces and lay on a silicone tray to freeze. I can then grab a handful to add to meals or put in with rice as a flavour, protein, collagen, fat and calorie boost at basically zero cost. And again, removed from the waste stream.
I grow galega cabbage, which is tall and perennial, so when I want a few cabbage leaves I just take off what leaves I want to use that day. I pick green onion, again, just what I want for that day. Same with herbs or comfrey or fat-hen (lamb's quarters). I don't over-stock the fridge with so much stuff that it blocks the view of what's in there else stuff gets buried at the back and forgotten. I learned that lesson long ago! Olives are brined and will keep for well over a year if necessary. Some surplus fruit is frozen. Some is turned into chutney. Bones are turned into bone broth and then given to the dog. No chickens or pigs or goats or donkeys these days, but ultimately there's a humanure heap with accepts anything that really can't get used, though most kitchen scraps get ruth-stouted under the mulch in the veggie garden.