Large potato chunks maximise contrast between the centre and exterior, creating a crispier result.
Russet and Yukon Gold are the best supermarket potato types for roasting. Russets have crispy crusts and fluffy interiors while Yukon Golds are darker, with a less crisp but flavourful crust. Red potatoes are not recommended as they lose their crunch quickly.
Pectin breakdown is crucial for texture, it’s affected by the pH of the cooking medium. Acidic conditions slow pectin breakdown, while alkaline conditions accelerate it.
For large potato chunks, alkaline conditions are preferable because they cause the exterior of the potatoes to break down more, creating a starchy slurry that leads to an extra-crisp exterior. Half a teaspoon of bicarbonate of soda for two quarts of water is recommended.
It’s advisable to start boiling potatoes in already-boiling water as opposed to cold water to promote exterior breakdown. The water should be well-salted to season the potatoes.
Roasting time varies due to the differing starch and sugar content in potatoes, relying on visual inspection and smell is suggested rather than strict timing.
A roasting temperature of 230°C is ideal. For fan ovens, 200°C is recommended. Potatoes should be left alone for the first 20 minutes and then flipped occasionally.
For added flavour, heat solid aromatics like minced garlic and rosemary in olive oil, strain the mixture, then toss the potatoes in the infused oil. The solids can be added back at the end along with fresh parsley.
These methods result in roast potatoes with a crisp crust, rich texture, and depth of flavour.