Technique · 5 versions tested

The Crispiest Roast Potatoes

Name: The Crispiest Roast Potatoes
Prep time: 20 min
Cook time: 55 min
Total time: 75 min
Yield: 6 servings
Cuisine: American
Ingredients: 3 lb floury potatoes such as russets, peeled and cut into large chunks; 1 tablespoon salt, for the water; 1/2 teaspoon baking soda; 3 tablespoons fine semolina; 1/3 cup neutral oil or duck fat; 4 sprigs rosemary; Flaky salt and black pepper

Everyone has an opinion about roast potatoes. We tested the main claims one at a time, with the same potatoes and the same oven, and the result was not quite what we expected.

20 minHands-on

1 hr 15 minTotal

6Servings

5Versions tried

The trial log

Every version we cooked, what changed, and the verdict. The highlighted row is the recipe below.

v1Raw potatoes straight into hot oilHard centres, no crust

v2Parboiled, not roughed upSmooth skin, mild crisp

v3Parboiled and roughed up in the panVery good crust

v4v3 plus a dusting of semolinaBest crust by a clear margin

v5v4 roasted at 450°FOutsides burnt before centres cooked

What the testing showed

Parboiling and roughing up do most of the work, and semolina adds a genuine improvement on top. Higher heat does not: at 450 degrees F the crust burned well before the insides were tender. The useful finding was that roughing up matters more than the fat you choose — we tested duck fat against oil in a side trial and the difference was far smaller than the texture of the surface.

The winning method

Heat the oven to 400 degrees F and put the fat in a large roasting tray to heat.
Boil the potatoes in salted water with the baking soda for 10 to 12 minutes, until the outsides are soft enough to scuff with a fork but the centres still hold.
Drain thoroughly and leave in the colander 2 minutes to steam dry.
Return them to the empty pot, put the lid on, and shake hard several times until the surfaces are visibly fluffed and ragged. Those edges become the crust.
Scatter over the semolina and shake again to coat.
Tip into the hot fat, turn once to coat, and roast 45 to 55 minutes, turning twice, until deep golden and audibly crisp. Add the rosemary for the final 10 minutes and finish with flaky salt.

The bit that matters

Rough them up more aggressively than feels reasonable. Every ragged edge is a future crisp bit, and gently tossed potatoes come out smooth and disappointing no matter how hot the fat is.

*Approximately 310 calories per serving. Calories are an estimate from standard ingredient databases; actual values vary by brand and portion. See our disclaimer.