Wherever you stand on the plastic straw debate, food writer Melissa Hemsley is right: "You don't get two in your mojito on a Friday night now!"

Things are undoubtedly changing. Call it the Blue Planet II effect, or simply an inevitable waking up to the demands we put on the planet, but more than ever before, the choices we make daily – and especially at dinnertime – come with a side of: is this environmentally justifiable?

It's an idea that threads its way through Hemsley's lively new cookbook, Eat Green. Veg-heavy (but not fully vegetarian), it focuses on all the little ways we can cut waste and get dinner on the table without feeling like quite such dreadful, energy-sapping humans.

The London-based 34-year-old, of sister double act Hemsley+Hemsley – best known for popularising the spiralizer, bone broth and cauliflower rice – calls it a guide on how to "get the most out of food, be frugal, be thrifty – but in a positive way".

"[For] my Roman catholic Filipino mum, throwing food away was a sin," says Hemsley of her upbringing, "which can make you feel guilty and is a bit preachy and scary. But I've really realised that for those of us who care about the planet, [the stats around food waste are] something we could all probably do with addressing."

She is well aware how easy it can be to succumb to the panic and despair those food waste statistics can induce; a third of all food produced is wasted somewhere along the line, and according to charity WRAP, 85 per cent of that waste happens at home.

"There is this deep sadness about what's going on in the world, but also, you go to marches and you talk to people about it, and there's also a very, 'We're all in this, let's get on with it' optimism. A, 'Let's share what we know and do the best we can' [attitude]," muses Hemsley, who cooked for Extinction Rebellion during several of the group's 2019 climate protests.

"But I agree that sometimes it can be so incredibly overwhelming that you don't know where to start. You might freeze, you might give up, or you just think, 'Ugh, I'll deal with it another day', and I understand that."

RECIPE: Parsnip Dahl Topped With Roasted Parsnips And Pink Pickled Onions

However, she adds: "I really feel lots of us can get behind food waste. It can tick so many boxes – saving money, doing your part for the planet. We mustn't, mustn't listen to this idea that what we do won't have an effect.

"Life happens," she continues, "things do end up in the bin, but what can we do to stop that happening as much as possible?"

Eat Green presents some of those possibilities. Packed with tips for using up some of the most binned fruit and veg items (looking at you, carrot tops and cauliflower leaves), it's positively boisterous, teeming with feelgood ways to stretch your food, fill your belly with good stuff and greenery, and make your cooking life a little easier.

Self-taught chef Hemsley encourages batch-cooking, cooking from scratch, avoiding plastic (wherever possible), not overusing the same ingredients (poor beloved avocados and chickpeas), eating seasonally, making a judgement on eating certain items past their sell-by-date, and being flexible ("My mum basically taught me: be flexible, use what you've got").

And that's not even mentioning her favourite thing; filling up the freezer, so all you have to do is defrost dinner in culinary Blue Peter style – here's one I made earlier. Ta-dah!

"I only feel good when I've got food in the freezer," she says with a laugh, describing how she recently had a nasty fall down the stairs and "genuinely had the thought in my head, 'At least the freezer is full'. Of all the things to cross my mind!"

She also hopes to help override that feeling we all get upon opening the fridge, that there's nothing to eat. That dinner can't be rustled up. "There is always something," says Hemsley. "So why waste your energy trekking out in the rain and the cold to the shops, to just go and spend more money?"

It's simpler if you have well-stocked cupboards and a chest-freezer of buried, edible treasure, of course. But Hemsley is clear – she just wants her recipes to be helpful and useful: "I don't want to tell anyone how to live their lives."

But if she does manage to help you cut waste and align better with the seasons ("I don't want to offer people cherry tomato recipes in December"), that can only be a good thing.

"What I do know is that every single one of us can play a part," she says, adamant. "With no judgement or guilt tripping, what can you, I, do, that feels sustainable in terms of, can we repeat it every day? And if so, let's do it, and let's keep on doing it."

Eat Green by Melissa Hemsley, is published by Ebury Press, £22.