Chọn khoai tây. Làm sạch khoai. Nếu cần, hãy cắt khoai tây thành khối đều nhau.

Given the above summary, write a detailed text in English for it.
The ideal potato is firm and smooth. It's not sprouting and doesn't have any green coloration – this indicates that it is starting to produce toxins and could have an undesirable taste and even lead to headaches or diarrhea. Be wary of potatoes with soft spots or blemishes, too. As for the type of potato, that's ultimately up to you. There are waxy potatoes, starchy potatoes, and all-purpose potatoes. Waxy potatoes (Rose Finn Apple, Russian Banana, Red Thumb) hold their shape better and are great for boiling or roasting. Starchy potatoes (Russet, Jewel Yam, Japanese Sweet Potato) are great for baking and frying. Check to see if the recipe requires them peeled or unpeeled and peel them if needed.  If they don't need peeled, scrub them under running water until they're about as clean as they're going to get. If they do need peeled, with your potato peeler or a sharp knife (be careful!), peel them above a bowl or the trash. This makes clean up a lot easier. Wash them after peeling for good measure. Potatoes take a long time to cook, hence why you're parboiling them, right? To make sure they all cook at the same rate, cut them to the same size. If some potatoes are larger than others, they may not be done at the same rate as the smaller ones. And, in general, the smaller the potato, the quicker it'll cook. If you have really big potatoes, cut them into quarters just to cut down on your parboiling time.