There are many ways to parboil potatoes, but the result is more important than the exact technique. The purpose of parboiling is to precook the potatoes because they can take considerable time to roast or pan fry from their uncooked state. The process should cook them partially but not fully, and then you can go the rest of the distance with a tasty sauce or fat for maximum flavor.
To parboil potatoes, cook them in boiling water for about a minute and then drain them thoroughly.
Parboil is simply the process of partially precooking a food, usually a vegetable, to cut down on cooking time and minimize the wild cards that come with cooking multiple ingredients together for the same dish. This precooking is accomplished by boiling, but since boiling imparts no flavor, you complete the cooking process by finishing the vegetables in a separate step through roasting, stewing or pan-frying. Potatoes are a natural fit for the parboiling process because of their long cooking time and the techniques that make them the most appealing, such as roasting.
How to Par Cook Potatoes
Cut your potatoes into 1-inch cubes and bring a pot of water to a boil. Use about 3 parts water to 1 cup potatoes by volume. Add the potatoes to the water; cook for 1 minute and drain immediately. Alternately, add the cubed potatoes to the water before you start the heating process; heat the water and potatoes until they come to a boil and then turn off the heat and drain immediately.
If you cut your potatoes into larger chunks, they'll take a little longer to parboil, and if you cut them in smaller pieces, they'll parboil more quickly. When in doubt, remove a piece from the pan and test it for doneness. It shouldn't be fully tender, but it shouldn't be completely crunchy either. Refrigerate parboiled potatoes if you aren't going to use them immediately because they'll continue to cook if they sit for too long.
Roasting Parboiled Potatoes
When you roast potatoes, you want to get a crispy, browned exterior. This depends on your potato pieces being as dry as possible and having no steam coming off them when you toss them with the oil, because the mixture of oil and water will make them soggy rather than crispy.
Let your potatoes stand at room temperature or in the refrigerator until you don't see any steam. This will take about 15 minutes in the refrigerator and about half an hour at room temperature, depending on how many potatoes you're cooling. Toss the cooled potatoes with enough oil to fully coat them, and season them with salt, black pepper, and the herbs and spices of your choice.
Roasted at 375 degrees Fahrenheit, parboiled potatoes will take about 45 minutes to reach an attractive level of doneness. At 425 degrees Fahrenheit, they'll take closer to half an hour. Exact timing depends on your individual oven and on how well you like your potatoes done. If you skip the parboiling process, the roasting step can take as long as a 1.5 hours at 375 degrees Fahrenheit and an hour at 425 degrees Fahrenheit.
Stewing Parboiled Potatoes
Parboiling potatoes is a good way to go if you're putting them in a thick stew that isn't going to cook for hours. You can use raw potatoes in a beef stew because the long, slow cooking time is sure to cook your potatoes fully, but if you're making a vegetarian stew or if you've cooked your meat separately before adding it to the stew, it's a good idea to cook your potatoes separately as well.
Add parboiled potatoes about 15 minutes before your stew is finished cooking if you want them to be very soft and give them just 10 minutes if you prefer them somewhat firmer. As always, allow extra time for large pieces and shave off a bit of time if your pieces are smaller.