17.6 Cooking vegetables: time, method and color

How long a vegetable cooks, and how, changes its color, flavor and texture. The words for these changes were met with raw produce: the pigments chlorophyll, carotenoids, anthocyanin and anthoxanthin; the flavor groups mild, Brassica and Allium; and the texture builders cellulose, pectin and hemicellulose. see chapter 4: What happens inside the produce

Testing cooking time

A simple test shows what time does. Cut about 1 to 2 cups of each vegetable into pieces of the same size: carrots peeled, washed and cut into ¼-inch slices; broccoli in thin, washed spears about 2 inches long; onions peeled, or skinned after a quick blanch, and cut into bite-size pieces.

• Boil the vegetable, and start timing when the water comes back to the boil.
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• At 3 minutes, take out a third and put it in a custard cup.
• Keep boiling until the vegetable is crisp-tender. Note the time and take out the second third.
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• Boil the last third for 5 minutes more and take it out.
• Compare the three cups for appearance, texture and flavor.

Then think it through:

• How did each color change?
• Did texture change the same way in every part of the vegetable, and why or why not?
• What caused any change in flavor?
• What does a short cooking time gain?

Testing cooking method

A second test compares methods. Prepare a cup of the same vegetable for each of four methods, cut evenly. Cook carrots and cabbage until crisp-tender, and onions until their flavor turns mild. Carrots stand for the mild group, cabbage for Brassica and onions for Allium.

• A little water, lid on. Use only enough water to stop scorching, about ¼ cup in a one-quart pan. Add the vegetable to boiling water, cover and bring back to the boil.
• A lot of water, lid off. Bring enough water to cover the vegetable to the boil, add the vegetable and bring it back to the boil without a lid.
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• Microwave. Put it in a 1-pint dish with 2 to 4 tablespoons of water and a tight lid or microwave-safe wrap. Cook on full power until done, stirring once.
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• Steamer. Put enough water in the base that it will not boil dry. When it boils, put the vegetable in the top, cover, and cook over fast-boiling water.
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Afterwards, ask:

• Did every flavor group give the same result?
• Do the best methods for flavor, nutrients and looks agree, and if not, what compromise makes sense?
• Why is it hard to give an exact time, or an exact amount of water?
• How do microwaved vegetables compare with the others?
• How should frozen vegetables be cooked differently from fresh?

Four quick techniques

• Blanch or parboil: part-cook in plenty of boiling water, to stop enzymes working or to make peeling easier. see chapter 7: Moist heat
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• Pan: cook very thin slices over high heat in just enough oil to stop sticking. You can add 1 to 2 tablespoons of water and cover the pan to make steam; shake the covered pan so nothing sticks.
• Sauté: in an open, shallow pan, cook in a little fat over fairly high heat, only until just done. Done right, the vegetables look translucent, not brown. see chapter 8: Sauté and pan-frying
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• Stir-fry: heat a little oil, add very thin slices and cook over medium-high heat, stirring all the time. A wok is best, but a large, deep skillet works. Keep each batch small.
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A method guide for common vegetables

Times below are approximate and are for prepared vegetables. Roasting is at 500°F, in one layer, tossed in a little olive oil and turned halfway. Steaming is in a covered basket over 1 to 2 inches of boiling water. Microwaving is on High, covered tightly.

Approximate times by method.

Tips for buying and preparing:

• Asparagus: fresh spears snap when bent; trim the ends and shave woody parts with a peeler.
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• Corn: it should feel heavy, with moist silks. To grill it in the husk, pull back the husk, remove the silks, close it again and leave the ears to soak for 20 minutes.
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• Zucchini: under 8 inches long they are sweeter, with fewer seeds.
• Leeks: split them lengthwise and fan the layers under cold running water to wash out the sand.
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• Spinach and chard: rinse them well, and leave the water on the leaves when they go into the pan.
• Frozen peas: cook them without thawing.
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Blanch first, finish later

Many vegetable dishes cook in two steps: a short boil to get the vegetable nearly done and set its color, then a quick finish in a pan or oven. see chapter 7: Moist heat

• Haricots verts (thin French green beans) boil in salted water for 2 to 3 minutes, then go straight into salted ice water to stop the cooking. Dried, they are warmed through in a sauté pan, in batches, with caramelized shallots and toasted almonds.
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• Brussels sprouts boil for about 5 minutes, until just slightly tender, then are halved and browned cut side down in olive oil with pancetta for about 10 minutes.
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• Asparagus is blanched in salted boiling water until just tender, cooled in an ice bath and patted dry, then warmed for about a minute in clarified butter with garlic and shallots.
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• For a gratin, broccoli or Brussels sprouts are boiled in plenty of water until nearly done, layered with a cheese sauce, topped with buttered crumbs and baked at 350 to 375°F for 15 to 20 minutes.
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Cooking with little or no water

Some vegetables need almost no added water. For panned spinach, wash the leaves by plunging and lifting them in water, again and again, until no sand settles in the bowl. Then cook them in a skillet with a tight lid for about 3 minutes, using only the water still clinging to the leaves.

Leeks get the same washing. Cut them in quarters lengthwise and then into 2-inch strips, lift them through the water until it runs clean, and put them into hot butter wet. Cook five minutes, add a little broth and lemon zest, cover, and cook about five minutes more until tender.

Halved winter squash bakes cut side down in a dish with boiling water ¼ inch deep around it. An acorn squash bakes at 400°F for 35 minutes, then is turned up, filled with apple, brown sugar, cinnamon and butter, and baked about 40 minutes more. A spaghetti squash bakes at 350°F for 45 to 60 minutes; its flesh is then pulled into strands with a fork.

Mixed vegetables roast well together when cut to one size. Sweet potato, red potato, carrot, fennel, green pepper and red onion in 2-inch pieces, tossed with olive oil, balsamic vinegar and seasoning, roast at 425°F for about 45 minutes, until tender and lightly browned. see chapter 8: What roasting is

Keeping cooked vegetables safe

Cooked vegetables are potentially hazardous foods. see chapter 2: Heat: cooling, holding and reheating

• Hold them hot at 60°C (140°F) or above.
• To cool them, bring them from 60 to 20°C (140 to 68°F) within two hours.
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• Then bring them from 20 to 4°C (68 to 40°F) within four hours.
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• Shallow pans, an ice-water bath and stirring all speed the cooling.
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