POTATO BASICS

THE COOK HAS TWO CHALLENGES WHEN preparing any recipe with potatoes. The first is to determine the best cooking method. How should potatoes be baked? What's the best way to make mashed potatoes? A second question is nearly as important. What kind of potato works best in a specific recipe? While other vegetables in most markets vary by size and freshness, in most cases, shoppers will find only one variety of that vegetable. Broccoli is broccoli, carrots are carrots. Even when there are several varieties (as with heirloom tomatoes), most can be used interchangeably. Yes, one tomato might look a bit different or be a bit sweeter than another, but they are closely related.

With potatoes, this is not the case. Make french fries with Red Bliss potatoes and the fries will be heavy and greasy. Use russet potatoes in salad and they will fall apart into potato mush.

The fact that dozens of potato varieties are grown in this country makes the question of which potato is best for a specific recipe even more confusing. At any time you may see as many as five or six kinds of potatoes in your supermarket. Go to a farmers' market and you may see a dozen varieties. Some potatoes are sold by varietal name (such as Red Bliss or Yukon Gold), but others are sold by generic name (baking, all-purpose, etc.)

STARCH CONTENT

To make sense of this confusion, it is helpful to group potatoes into three major categories based on their ratio of solids (mostly starch) to water. The categories are high-starch/ low-moisture potatoes, medium-starch potatoes, and low-starch/high-moisture potatoes.

Each of the recipes in this book has been tested with all three major types of potatoes. In each recipe, we have listed the commonly available variety that works best.

You can safely make substitutions within each category (for example, other varieties of red potato can be used in place of Red Bliss potatoes in salad). Substitutions between categories are more problematic. In a few recipes, such as potato gratin, different potatoes give different results, but all are acceptable. In most cases, however, one type of potato is clearly preferred.

HIGH-STARCH/LOW-MOISTURE POTATOES

Often referred to as baking potatoes, high-starch/low-moisture potatoes can also be used for frying and mashing. The flesh in these potatoes turns dry and fluffy when cooked. Russet potatoes (also called Idaho potatoes) are the most common baking potatoes. Other lesser-known varieties include the All Blue and White Creamer. In all of our recipes, we refer to baking potatoes as russets.

MEDIUM-STARCH POTATOES

These potatoes are considered all-purpose and include Yukon Gold, Yellow Finn, Purple Viking, Caribe, Irish Cobbler, Butterfinger, Ozette, and Purple Peruvian. All-purpose potatoes can be mashed or baked but are generally not as fluffy as the high-starch potatoes. Likewise, they can be boiled for salad, but they won't hold their shape as well as red potatoes. We generally recommend medium-starch potatoes in recipes for dishes such as home fries, where a combination of these traits is desirable.

LOW-STARCH/HIGH-MOISTURE POTATOES

This category covers all red-skinned potatoes, including Red Bliss, Red Pontiac, All Red, Dark Red Norland, Ruby Crescent, and Red Creamer. It also includes most new potatoes as well as the Rose Finn Apple, the Russian Banana, and the White Rose potato. All of these potatoes, often called waxy potatoes, hold their shape better than other potatoes when sliced or diced and cooked. They are best roasted, sautéed, or boiled and used in salad.

STORAGE POTATOES VERSUS NEW POTATOES

In addition to categorizing potatoes by starch content, it is useful to divide them into two groups based on how they have been handled after harvesting.

STORAGE POTATOES

Most potatoes are cured after harvesting to toughen their skins and protect their flesh. They are then held in cold storage, often for months. These potatoes are called storage potatoes. Almost all of the potatoes in supermarkets are storage potatoes.

NEW POTATOES

Occasionally potatoes are harvested before they have developed their full complement of starch. New potatoes are always waxy (low in starch, high in moisture), even if they are actually a high-starch variety. Although all new potatoes are small, not all small potatoes are new. You can pick out a new potato by examining the skin. If the skin feels thin and you can rub it off with your fingers, you are holding a new potato. New potatoes have a lot of moisture and their flesh is almost juicy when cut.

SWEET POTATOES

Finally, there is the sweet potato. This tuber is in fact not a potato at all. It is part of the morning glory family. The kind of sweet potato found in most markets is orange-fleshed (they are labeled yams but are not related to the tropical plant of that name), but yellow-fleshed varieties are available in some markets. For more information on buying and cooking sweet potatoes, see.

KEEPING POTATOES AT HOME

Since potatoes seem almost indestructible compared with other vegetables, little thought is generally given to their storage. But because various problems can result from inadequate storage conditions, we decided to find out how much difference storage really makes. We stored all-purpose potatoes in five environments: in a cool (50–60 degrees Fahrenheit), dark place; in the refrigerator; in a basket near a sunlit window; in a warm (70–80 degrees), dark place; and in a drawer with some onions at room temperature. We checked all the potatoes after four weeks.

As expected, the potatoes stored in the cool, dark place were firm, had not sprouted, and were crisp and moist when cut. There were no negative marks on the potatoes stored in the refrigerator, either. Although some experts say that the sugar level dramatically increases in some potato varieties under these conditions, we could not see or taste any difference between these potatoes and the ones stored in the cool, dark but unrefrigerated environment.

Our last three storage tests produced unfavorable results. The potatoes stored in sunlight, in warm storage, and with onions at room temperature developed a greenish tinge. When potatoes are stressed by improper storage, the level of naturally occurring toxins increases, causing the greenish tinge known as solanine. Because solanine is not destroyed during cooking, any part of the potato with this greenish coloring should be completely cut away before cooking.

The skin of the potatoes stored in sunlight became gray and mottled, while the potatoes stored in a warm place and those stored with onions sprouted and became soft and wrinkled. Sprouts also contain increased levels of solanine and should be cut away before cooking.