If there is one cooking trick that I could teach you to make your meals better, I would pick the technique of caramelizing onions.

You’ve probably had dishes that pretended to contain so-called caramelized onions, which may have even left you wondering what the fuss was about. These pretenders might have been pale and soupy, or wretched with added sugar to fake you out. They may even have been in a recipe that said to sauté onions for “15 minutes, until caramelized.”

Hah. 15 minutes. You’re just getting started at 15 minutes. I’m asking you to give these onions at least two hours — because good things are worth waiting for.

Onions are the inexpensive workhorse of the kitchen. A bag of onions can sit for weeks.

They can also make you cry. Each onion holds sulfur precursors and enzymes in separate tissues. When you start slicing, the chemicals mix, creating the spicy sulfur that mixes with your tears, and you know what happens next. Eaten raw, they add a bite to a salad or sandwich. When cooked, the tear-producing compounds are deactivated. Then the natural sugars can shine.

The chemistry that goes on when you cook onions low and slow is complex, but suffice to say that you are both caramelizing sugar and creating a “Maillard Reaction,” where sugars interact with proteins over heat, causing browning. In the process, a specific sulfur compound gives the onions a meaty taste.

The anonymous genius who invented French Onion Soup knew nothing of chemistry, when she created a classic from a few pennies worth of onions. All you really need to know is that you should take the time to do it properly.

There are no shortcuts, but there is one way to make it easier on yourself. You can toss the slivered onions in oil and put them in a slow cooker, covered, on low heat overnight. What you’ll get in the morning will be very wet, so transfer the onions and liquids to a large skillet and cook them over medium heat, stirring frequently, until they become thick and sweet, about 15 minutes.

Once you have your caramelized prize, add sweetness and complexity to soups, salads, sauces, pizza and sandwiches like this one. The sweet, soft onions are sparked with tangy, salty blue cheese, crunchy slivers of pear, and a handful of fresh spinach makes it pop.

You’ll wonder how you ever got along without them.

Caramelized Red Onion and Blue Cheese Panini

Makes 4 sandwiches.

Note: Plan ahead, as the caramelization takes about 2 hours. Be sure to slice the onions from root to tip, not around the equator, to get the best results. Vegans can sub their favorite tangy nut-cheese, or even marinate crumbled tofu in vinegar and salt for a feta-like presence. From Robin Asbell.

• 2 lb. red onion (2 big ones), sliced root to tip to make 8 c. slivers

• 2 tbsp. extra-virgin olive oil

• 1/2 tsp. salt

• 3 oz. (1/2 c.) blue cheese, crumbled

• 2 small pears, cored and sliced

• 2 c. baby spinach, washed and dried

• 1 large baguette, halved for sandwiches

• Oil for grilling

Directions

In a large sauté pan, warm the olive oil over medium-high heat. Add the onions and stir, carefully, to coat with oil. Cook, stirring frequently, over medium-high heat for about 5 minutes, until the onions are sizzling and starting to soften. Sprinkle with salt. Reduce to medium-low and stir every 15 minutes for at least 2 hours. The onions will shrink down to about 1 1/4 cup. When they are melted and sweet, take off the heat and scrape into a small bowl. This can be done up to a week ahead of time.

To serve, crumble the blue cheese into the bowl and fold into the onions. Open up the baguette pieces and divide the onion mixture between them, spreading it on the lower piece of the bread. Cover with sliced pears and spinach, and close the sandwiches.

Preheat a panini grill on high, and brush the sandwich with oil. Place 2 sandwiches on the grill and close the top. Grill for about 4 minutes, then serve hot.

Alternative stovetop instructions: Heat 2 large cast-iron skillets over high heat for 3 minutes. Place 2 sandwiches in 1 pan, then place the other pan on top. Reduce heat to medium and cook for 3 minutes per side.

Nutrition information per serving:

Calories 520 Fat 20 g Sodium 1,050 mg

Carbohydrates 73 g Saturated fat 6 g Total sugars 20 g

Protein 16 g Cholesterol 15 mg Dietary fiber 7 g

Exchanges per serving: 1 fruit, 3 starch, 1 carb, 1 high-fat protein, 2 fat.

 

Robin Asbell is a cooking instructor and author of “Big Vegan,” “The Whole Grain Promise” and “Great Bowls of Food.” Find her at robinasbell.com.