Karma, it transpires, is real. If you are a regular Good Food reader, you might remember me as The Age's former restaurant critic, who last year, in the middle of lockdown 487, was asked to test out an air fryer. The benchtop apparatus claiming to be a healthy alternative to a deep fryer was gripping the internet. Inquiring minds needed to know whether the hype was real.

That tiny experiment last year revealed that thanks to an air fryer's condensed size and rapid air movement, they do trump your oven if you want to achieve crispness fast. Cooking crumbed items or small-batch reheating jobs were a cinch. Takeaway pizza that had languished on its trip home rose from the dead deliciously. Same went for crisping croissants, which usually become dry by the time your cavernous oven had heated them through.

But many questions were left unanswered. I worried about the longevity of a $40 machine – would it break after a few dinners? I predicted that home-made wet batters would need the kiss of hot oil, and that whole roasts would need the might of a big oven (surely the 3.5 litre bucket was too small?) Would the perks translate if you had to invest in the bulkier and more expensive models to feed four people?

Three months after writing that story, I moved to a farm and discovered the only oven came furnished with a fossilised pie and a rat, immortalised while chewing through the wiring. Once I'd chucked it in the skip, all I had to cook with was my air fryer.

So welcome to Air Fryers: The Rematch, in which I set out to discover how far I can push these gadgets. Can you really boil an egg? Is bigger better? And do we need the rest of our kitchen at all?

The year of living range-lessly

I've been consistently impressed at how the market's most low-tech air fryer has outperformed an oven in numerous recipes I'm familiar with. And it's not just cooking fried guff either.

This summer, my garden produced a glut of capsicums and tomatoes, which I plucked and placed directly into the bucket, rinsed in situ (the vents act like a handy colander), seasoned, oiled and charred in less than 10 minutes. What I didn't eat immediately, I oiled and put into jars or pickled and still have in the pantry as go-to antipasti.

So if small is successful, surely bigger is better? If a flimsy 3.5-litre thing can do so much, what could be achieved with Mistral's family-size 25-litre behemoth or with a top-of-the-range 22-litre multifunctional Breville Smart Oven Air Fryer? A croquembouche? World peace?

A proper retest clearly needed a more balanced approach. Scientific rigour dictated that I compare the might of the mini against the maxi market options in three categories: frying chips, roasting a whole chicken and baking a cake.

For the latest round of experiments I updated to the 2022 version of my trusty 3.5-litre Mistral, which is no longer available. The new machine has a slightly larger capacity (4 litres) and a digital interface – plus at $70, a higher price tag.

Round one: Chip champ

Who doesn't love a hot chip? That's a rhetorical question, but on the flip side, who doesn't hate a bad chip? Too brown, too soggy, too dry. For a seemingly simple dish of fried carbs, so much can go wrong.

For heat one I divided a bag of frozen straw fries (the chip with the slimmest margin of error) between the three air fryers. Each machine has its own pre-set temperature and time for fries, so you simply have to dial to that setting and hit go.

The verdict: The Breville blitzed this challenge. The machine's larger capacity meant the chips were evenly spread out, allowing maximum air circulation without having to shake the chips around. The timing preset was also perfect, whereas in the Mistral 25-litre, the chips were starting to brown with seven minutes left on the clock and might have burnt had I let the program run. The bucket was also right on time, but you need to remember to keep shaking the chips to ensure even cooking.

Also try: Frozen beer-battered fish, nostalgic snacks such as Chiko Rolls and finger foods like nuggets, spring rolls and battered broccoli florets can get you out of a last-minute party pickle.

Round two: Roast with the most

For the sake of this exercise I skipped the big Mistral to compare the Breville with the bucket and a regular oven. I took three chickens of equal weight, patted them dry, and seasoned them only with olive oil, salt and pepper.

The verdict: Get yourself a benchtop bucket air fryer pronto. Set it at 200 degrees. Cook the bird for 30 minutes a side (breast up, then breast down). Call yourself a genius. To be fair, the big Breville also did a beautiful job. The original settings will deliver a crisp bird with a juicy centre. But both the appliance and the standard oven are of a size that means you have greater moisture loss due to evaporation. In a regular oven, you could temporarily cover your bird with foil, but that's a safety no in the Breville (it can cause a fire) and who wants the extra hassle? While I originally said I "probably" wouldn't cook a chicken in the tiny thing, I will henceforth never use anything but a fryer.

Also try: A duck may be too big for a fryer, but remove the legs (save them to slow cook), salt and dry the crown in your fridge for at least a day, then cook hot and fast for 45 minutes at 200C for crunchy skin and plush flesh.

Round three: Baker deluxe

Yes, you can bake in a small air fryer, something I've discovered under duress without a kitchen. But it's not what they were built for. Air frying harnesses radiant heat, convection and conduction, which together create a fiery vortex. That's not ideal for delicate pastry, cakes or quiches, which require consistent and sometimes more subtle distribution of heat. To put them to the test, I whipped up three packet cake mixes and cooked them at the temperatures recommended for each of the air fryers.

Extracurricular frying

Caveat emptor, friends. When you buy an air fryer, you are also buying into a bizarre subculture. These machines are built to roast birds and crisp a chip. But the internet demands to know whether it can boil an egg and deep-fry a Mars Bar. Admittedly, I wanted to know too. Let's start with the good.

Roast yourself fit

You know who loves a fryer? Gym geeks doing meal prep. And I am with them. Don't sell your air fryer short by only cooking "healthier" chips. Go bigger. Whole Brussels sprouts cooked in that piping hot environment have an extra crisp exterior and are still cabbage sweet at heart. Take a pumpkin quarter, score the flesh deeply (almost like a hasselback potato), season with oil, fennel seed, cumin and garlic and cook until the sugars caramelise and the flesh is soft. Splash on yoghurt to finish and that's a side dish or a central party piece. I can also report that if you put a whole head of cauliflower in the microwave with salted water for 10 minutes, then oil it up and airfry for 35 minutes, you have the globally beloved star dish of Miznon restaurant on your table in exactly half the traditional cooking time.

Boiled eggs

Does this really work? Boiled eggs without any water? It does. Now, I tried this in both the Breville and my bucket air fryer. The instructions said to cook at 135C for 11 minutes for a runny yolk, through to 15 minutes for a classic hard-boiled egg. The key (as with hard-boiled eggs done the usual way) is dropping them in an ice bath immediately afterwards. The bucket fryer delivered. The Breville didn't get them nearly hot enough because it was too big to deliver the same radiant heat in the time listed. I could have cooked them for longer. But then again, boiling an egg in water only takes seven minutes, which to my mind makes you the hack, not this trick.

The deep-fried Mars Bar

When I polled friends and followers on what they wanted me to test, one item kept coming up: Scotland's trashy treat, the deep-fried Mars Bar (narrowly edging out deep-fried ice-cream). It was disastrous. I had zero success at adding a DIY wet batter to anything, from tempura veg to this chip shop classic, no matter how hot I set the machines or how well they were pre-heated. I even froze the central ingredient to give the exterior time to "set" into a crisp tomb, but in every case I ended up with pools of gak on the airfryer floor. Zero stars.

The last word

So. What the hot crispy heck is the deal? Do you need one of these gadgets? If so, which one?

Here's the thing. Unless you, like me, have no kitchen to speak of, all the extra bells and whistles that come with the bigger machines are largely just doubling up on your oven.

But a year in, I am sold hook, line and sinker on the benefits of air frying. And it has nothing to do with making "healthier chips".

The speed, size and portability of a small, cheap, benchtop machine are the main positives.

Beyond getting a crisp finish on a dish without dehydrating, it has given me so many wins, from being able to cook in a tiny space (including on holiday at kitchen-less Airbnbs) to keeping kids happy with nuggets at a garden party. The interface is idiot-proof (no need to read a manual!), and the energy-efficiency of using a small device rather than heating a whole oven has neutralised my concerns about the environmental impact of buying the gadget to begin with.

Did I mention the washing up? With the bucket-style machines (you can get a bigger bucket-style fryer if you need to cook for a family), you can remove said bucket and chuck it in the dishwasher. Job done. The benchtop ovens come with numerous accessories (in the case of the 25-litre Mistral, they include a frying basket, drip tray, pizza dish, and a rotisserie), all of which can go in the dishwasher too. But the ovens themselves became absolutely coated with grease and require a classic oven clean.

The Breville and 25-litre Mistral are certainly more high-tech gadgets. I'm sure they will outlast my small device. They both have many functions – warming, slow cooking, dehydrating, pizza-making, delicate baking – and are smaller than a conventional oven while still being capable of cooking quite large items. They are also electric, if you are weaning yourself off gas. But you lose many of the perks of the simpler machine. With greater capacity comes less speed, and therefore more power usage. You need a dedicated bench, and they aren't light. If you have a decent kitchen, do you really need a bulky oven clone? Maybe not. That said, if you're kitchen-less (hello, students and everyone displaced by the rental crisis), these bigger machines represent a pretty full service kitchen in a box.

Keen to fry and want to know which one to try? This is a rare case where the million-dollar question has a $70 answer.

The writer independently tested the following machines for this story:

Mistral 4 Litre Air Fryer, $70

Mistral 25 Litre Multi-Function Air Fryer Oven, $149

Breville Smart Oven Air Fryer, $599.