Onions are biennials, that is, they form a bulb the first year of growth (this is what we eat) then send up a flower and form seeds the second year of growth. One way an onion bulb gets a jump on reproduction is to be light sensitive. As the days grow longer after the Winter Solstice on December 21, the onions in our larders sense spring is on the way and begin getting ready to send up a flower stalk. The best storage onions delay this process, but as soon as we begin getting over ten hours of light a day (where I live, that’s in February) even the best keepers are usually turning green in the middle and getting soft. So right about the time I start planting next year’s onions (around twelve weeks before the last frost) it’s also time to do something with last year’s onions before they go bad.

My favorite way to use up onions is to make a big batch of caramelized onions. Sweet, melting, golden caramelized onions are used in regional cuisines all over the world. In Greece, they are mixed with sheep milk yogurt and tossed with pasta and grated cheese, or served atop a dish of lentils and parsley. In France, where they are called “confit d’oignon” they turn up beside grilled meat or mingled with bacon and cheese in quiche. Tuscans strew them over their regional flatbread, schiacciata, along with a little cheese and a few olives to make a light lunch.

But no matter what dish the onions wind up in, they are caramelized the same way in every nation – slowly and carefully. The transformation of sulfurous raw onions into lush onion confit is caused by the same chemical reaction that makes baked goods golden on the outside or turns cream cooked with sugar into tawny caramels. This is called the “Maillard Reaction” (named for the French scientist who first described it in 1912) and it is one of the most important processes in cooking.

The Maillard Reaction is not, in fact, caramelization, which occurs when sugars alone are exposed to high heat and turn brown. Rather, the Maillard Reaction requires both amino acids (the building blocks of proteins) and sugars, which, when exposed to gentle heat, react with one another to form hundreds of new and delicious compounds.

If the heat is too high and the cooking too fast, the by-products of the reaction turn black and bitter (think burned toast). Burned food not only tastes bad; it’s probably unhealthy. There’s some evidence that charred food may be carcinogenic.

Traditionally, caramelizing onions is as labor intensive as making risotto, requiring long-stirring and careful watching. Luckily there’s an alternative that involves very little labor – caramelizing them overnight in a slow cooker.

Eight cups of thinly sliced onions will reduce to just three luscious cups. Pop them in your refrigerator and you’ll have a base for any number of dishes. Below you’ll find three of them. The first, a vegetarian onion soup, is to my taste buds even better than the traditional French version made with beef stock (though feel free to use meat stock if you’d like).

The second is a dish traditionally served during the Muslim holy month of Ramadan, eggs poached in caramelized onions and delicately seasoned with cinnamon. Served with toast and a salad, it makes a delicious light supper.

And finally, here’s my take on that old standard, onion dip. Feel free to tinker with this one, especially if you’re avoiding fat. It’s delicious made with just non-fat yogurt, in which form it’s great tossed with pasta or topping a dish of sauteed spinach and garlic.

Caramelized Onions

(about 3 cups)

• 2 tablespoons butter
• 2 tablespoons olive oil
• 8 cups thinly sliced onions (about 10 onions)
• salt and pepper to taste

The easiest, most sure-fire way to caramelize the onions is in a slow cooker. Turn the slow cooker to low and add the butter and olive oil. When the butter has melted, add the onions and a pinch of salt then stir to coat them in the oil and butter. Put the lid on the cooker and leave the onions to caramelize for 6 hours or longer. Putting them on just before bed and allowing them to cook overnight works well. They are done when they have turned a deep golden brown.

Otherwise, melt the butter in a large, heavy pot over medium heat. Add the olive oil and swirl, then add the onions with a pinch of salt and stir well. Reduce the heat to low and cook the onions very slowly, stirring occasionally. If you can’t watch the onions like a hawk, put a lid on the pan. The onions should not brown immediately but should slowly melt and turn a deep golden color. Without a lid, this will take 30-45 minutes. With a lid on the pan, this can take two or three hours.

When the onions have caramelized, add more salt if necessary and pepper to taste. The onions can be stored in a jar in the refrigerator for a week, or frozen for up to 3 months.

Caramelized Onion Soup

(serves 8)

• 1 recipe Caramelized Onions
• 4 cloves garlic, peeled and chopped
• a few sprigs fresh thyme or 1/2 tsp. dried thyme
• 2 tablespoons tomato paste (omit if using tomato water)
• 1/2 cup white wine
• 7 cups water, stock or tomato water (see note)
• salt and pepper to taste

For Serving:

• 8 ounces melting cheese, grated (Gruyere is traditional)
• 8 slices toasted European Style bread

Add the garlic, the thyme and the tomato paste to the onions and let them bubble together for a few minutes. Add the wine and simmer the mixture carefully until about half of the wine has evaporated. Add the water, stock or tomato water and simmer for 20 minutes. Add salt and pepper to taste.

To serve, turn your oven to broil or high heat. Place 8 serving bowls on sheet trays, fill with soup, top with a slice of bread, then sprinkle the bread with cheese. Place the bowls in the oven until the cheese melts and browns a little. Serve immediately.

Note: Tomato water is the clear liquid drained from chopped fresh tomatoes. I collect this in summer when I’m processing tomatoes for roasting or sauce making. Tomato water is full of flavor and shouldn’t be discarded. It can be used fresh as a broth or beverage and freezes well for use all winter long. It is particularly good as a soup base.

Turkish Eggs with Caramelized Onions

(serves 4; adapted from The Turkish Cookbook by Nur İlkin and Sheilah Kaufman )

• 2 cups Caramelized Onions
• 1 tablespoon best quality vinegar (sherry wine vinegar works well)
• 1 teaspoon sugar
• 1/2 cup water
• 4 eggs
• a pinch of cinnamon
• salt and pepper to taste
• 4 slices of buttered toast

Place the onions in a large skillet over medium heat and bring to a simmer. Add the vinegar, sugar and water and allow to bubble for a minute or two. Use a spoon to make four nests in the onions and then crack an egg into each of the nests.

Sprinkle a little cinnamon over the eggs and onions, then a little salt and some freshly ground pepper. Put a lid on the skillet and simmer the eggs and onions until the egg whites have set all the way through but the yolk is still soft and runny inside.

Meanwhile, place a slice of buttered toast on each of four warm plates. When the eggs are done, use a large spoon to carefully place one of them and some onions on each slice of toast. Serve immediately.

Caramelized Onion Dip

• 4 ounces cream cheese, softened
• 1/2 cup Greek style yogurt (or regular yogurt, drained for an hour or two in a sieve to thicken) or 1/2 cup sour cream
• 1/2 cup mayonnaise
• juice of 1/2 lemon
• 1 small bunch scallions or chives, minced
• 1 cup Caramelized Onions
• 1/2 teaspoon paprika (smoked paprika is good)
• 1/2 teaspoon Tabasco or other hot pepper sauce (optional)
• salt and pepper to taste

Mix the cream cheese with a wooden spoon to soften then add the yogurt and mayonnaise and combine well. Stir in the lemon juice, the scallions or chives, the Caramelized Onions, the paprika and Tabasco. Taste before seasoning with salt and pepper if desired. Cover and refrigerate for an hour or two, allowing the flavors to meld before serving. This is good with chips as well as raw vegetables and a good, crusty sliced bread.