Quick and Easy Caramelized Red Onions (20-Minutes Only!)

Caramelized Red Onions are a side dish made with just 5 ingredients: brown sugar, balsamic vinegar, butter, salt and, of course, onions, usually red, but also white or golden. Quick and easy, they are incredibly versatile: they go well with meat-based main courses, such as burgers or roasts, fish dishes, such as seared tuna, but they are also perfect for filling sandwiches, pizzas, focaccias , savory pies and piadinas.

Colorful and delicious, they are ideal for a brunch with friends or for a party buffet. Excellent when ready, they are even better after a day of rest.

What Are Caramelized Red Onions?

Caramelized onions, including the red variety, have long been a staple in kitchens worldwide, praised for their sweet, rich flavor that transforms ordinary dishes into something special. The process of caramelizing onions dates back centuries, originating in French cuisine, where slow cooking onions in butter was used to bring out their natural sweetness. Red onions, in particular, offer a slightly milder, tangier flavor that works beautifully with the addition of balsamic vinegar, a classic Italian pairing. Famous variations include French onion soup, where caramelized onions form the base, and Indian dishes like biryani, where fried caramelized onions add a burst of flavor.

Fun fact: caramelizing onions takes patience—some chefs refer to it as “onion therapy,” as it requires slow, careful attention for about 30-40 minutes to achieve that perfect, deep golden hue!

Pro Tips for The Best Caramelized Red Onions

• Cut the onions into uniform slices to ensure they cook evenly and caramelize at the same rate.
• Cook the onions over low heat, allowing them to caramelize slowly without burning or browning too quickly.
• A mix of butter and a little oil prevents the butter from burning and gives the onions a rich flavor.
• Brown sugar helps intensify the sweetness, but don’t overdo it—just a tablespoon will enhance the flavor without overpowering the onions.
• Add salt at the end to avoid drawing out too much moisture early on, which can prevent proper caramelization.

What Is The Secret For Perfect Caramelized Red Onions?

The secret of this preparation lies in the slow cooking, which makes the onions very soft and melting on the palate.

Can I Use Another Type of Onion for This Recipe?

Yes, you can use other types of onions for this recipe! Yellow, white, or even sweet onions like Vidalia will caramelize just as well, though each will bring slightly different flavors. Yellow onions offer a more robust flavor, while sweet onions, as the name suggests, will result in an even sweeter caramelization. Red onions, however, have a unique tanginess that pairs perfectly with balsamic vinegar.

Butter or Oil? Which One's Best to Caramelize Onions?

Both butter and oil can be used to caramelize onions, but the best results come from using a mix of the two. Butter adds rich flavor, while oil (like olive or vegetable) helps prevent the butter from burning due to its higher smoke point. This combination ensures the onions caramelize slowly and evenly, achieving that perfect golden-brown color without any bitter, burnt taste.

How Do I Make Sure These Onions Are Caramelized Evenly?

To ensure your onions caramelize evenly, slice them uniformly so they cook at the same rate. Cook over low heat and stir occasionally to prevent sticking or burning. Patience is key—let them cook slowly without rushing the process, and avoid crowding the pan, which can cause steaming instead of caramelizing.

What Pan Should I Use For This?

The best pan for caramelizing onions is a wide, heavy-bottomed skillet or sauté pan, preferably made of stainless steel or cast iron. These pans distribute heat evenly, allowing the onions to cook slowly and develop a deep, rich caramelization without burning. A wide surface area also prevents overcrowding, ensuring even cooking and perfect results.

What Can I Use These Caramelized Red Onions For?

They’re perfect for topping burgers, sandwiches, or pizzas, adding richness to pastas and risottos, or serving as a sweet, savory side with meats like steak or chicken. They also make a great base for French onion soup or can be mixed into dips, tarts, and quiches for extra depth of flavor.

Can I Make These Onions in Advance?

Of course! After cooking, let them cool and store in an airtight container in the fridge for up to 5 days.

Do These Caramelized Onions Freeze Well?

They do! After cooling, transfer them to an airtight container or freezer-safe bag, and they’ll keep in the freezer for up to 3 months. When you're ready to use them, simply thaw and gently reheat.

More Onion Side Dishes You Have to Try!

Grilled Onions

Roasted Onions

Onion Salad

Pickled Onions

Fried Onions

Roasted Flower Onions

Onion Fritters

How to Store Caramelized Red Onions

Caramelized red onions can be stored in the refrigerator, tightly closed in an airtight container, for up to 4 days.

How to Make Caramelized Red Onions

Peel the onions and remove the ends and cut them into slices about 3-4mm thick.

Place a generous knob of butter in a large pan and let it melt completely.

When the butter has melted and is lightly browned, add the onions.

Let them cook on a low flame for a few minutes, stirring occasionally, until they begin to soften.

At this point, add the brown sugar and mix to distribute it and melt it.

Complete with balsamic vinegar, then let the onion cook on low heat.

The onions should be well caramelized, with an intense and shiny color. Season with salt and mix again to let them get flavored.

Once cooked, transfer them to a small bowl and let them cool for a few moments before bringing them to the table.

Enjoy!