Ask Peter: How to cook the perfect roast potatoes
I’m originally from the UK and although I’ve lived in New Zealand for over 10 years, I still enjoy a roast dinner on Sundays. One thing I can never get right is my roast potatoes. Every recipe I read has a different technique and a different choice of oil. What would you recommend for the crunchiest roasties?
The thing with potatoes (and I’m not including kumara here) is that there are basically two types, and each type is best suited to different uses.
In “potato world” you have floury potatoes and waxy potatoes — and each perfectly describes the texture of the potatoes themselves once cooked. As a potato is pretty much just made up of starch and water (obviously there’s other things in the tuber such as vitamins etc, but let’s ignore that right now), the more starch there is in a potato, the more floury it is.
Waxy potatoes have a much higher water content, a denser structure, and are lower in starch (good for weight watchers). Because they’re “waxy” they hold their shape, absorb less of any dressing they’re tossed with in a salad, and can become slightly lumpy if mashed, as they’re harder to make smooth.
Those of you who grow potatoes will be aware that a potato can also change in texture throughout the season and some potatoes, therefore, can be considered both floury and waxy.
In 2008 I was asked to be the “face” of the International Year of the Potato here in the UK. I was asked because the British potato council felt I’d have a global view on spuds rather than a regional one —which would encompass Indian potato samosas, Italian gnocchi, duck fat roasties from New Zealand, potato pancakes from Scandinavia and rosti from Switzerland along with dishes around the world.
Needless to say I did my research and found out some fascinating facts about this delicious and nutritious vegetable. One of those things was that a New Zealand ilam hardy spud will begin the season in October as a waxy potato, which is great for salads and boiling, but as the months move on the sugars in it begin to convert to starch and so by the end of its season it’s become a floury example which is better suited to roasting, chips and mash.
This doesn’t mean it’ll be a fantastic floury potato, but it’s a versatile one. I knew the potato originated in the South American Andes, but I didn’t know those first tubers began growing around 8000 years ago. In 1570 the spud arrived in Europe, then European sailors took it to China in 1609.
China is now the world’s largest producer, and almost a third of all potatoes are harvested in China and India. Potatoes headed to America in 1719, and in 1801 the first French Fries were served there.
Potato crisps were invented in New York in 1853 and in 1995 they grew the potato in space! But I digress.
Waxy potatoes tend to be early new season varieties like red king edward, nadine, jersey benne and others. These are great boiled then sliced and added to salads or served warm topped with butter and some grated parmesan cheese. General purpose spuds include desiree, rua and karaka — and these can work in both the waxy and floury camp.
Floury spuds, great for mash, chips, baking and roasting, include agria, laura, ilam hardy and red rascal. As to how best to roast a spud — peel and cut your potatoes into large chunks. Boil in generous amounts of fairly heavily salted water until you can almost poke a knife through. Drain and leave in the colander for 5 minutes, then place back in the saucepan and put the lid on.
Shake the pan quite vigorously from side to side — which smashes the outside and makes it look slightly mashed. It’s this mashed texture that will give your spuds lots of crunch. Place a roasting dish on the heat (if it’s metal) otherwise heat up a wide frying-pan.
Place 1 cm oil / duck fat / 30-70 per cent butter and vege oil into the dish once it’s hot and when almost smoking (turn on your extractor) carefully add a layer of potatoes. Cook until golden then carefully turn over and bake in the oven at 180C until the potatoes are golden and crisp — you may need to turn them a few times while cooking.
Sunflower, peanut and canola oils work well. Olive oils that aren’t extra virgin are also good. If you use only butter it will burn, so mix it up with 1 part butter to 2 ½ parts oil. And you’re better to slightly overcook your roasties than to undercook them — they’ll be more crunchy that way.
In our Ask Peter series, executive chef Peter Gordon answers your curly culinary questions. If you're stumped over something food-related, send your question to firstname.lastname@example.org and keep checking in for answers. You can read more on Peter on his website, have a read of his Ask Peter articles or check out his recipes on our site.