Balsamic Pickled Onions with Garlic Mustard Seeds

Pickled onions are a staple in my home. I use them to garnish dishes, but they are especially great on salads. The combination of the sweet, sour, and salty flavors is just irresistible. I love to eat them straight out of the jar, too!

Pickling onions are easy to do and don't take very long to complete. First, however, you will need an item from the pantry: a small quantity of vinegar, a red onion, and a couple of other ingredients. This can make the difference between ordinary pickling onions and ones that are tangy, sweet, and sour in ways that you never thought possible.

Jump to:

• Why I love these Easy Pickled Red Onions:
• Ingredients
• How to pickle red onions
• Variations
• Serving Suggestions
• Storage
• FAQs
• 📖 Recipe
• Related recipes
• 💬 Comments

Why I love these Easy Pickled Red Onions:

These red onion quick pickles are a staple in our home. I make them all the time, and they are great for adding to salads, sandwiches, and appetizers. Pickled red onions are zippy, sweet, and crisp with vinegar zing. It takes less than fifteen minutes to make a batch of pickled onions, which they keep in the fridge for a few months.

Feel free to scale up this recipe if you have a lot of onions on hand. They'll keep well in the refrigerator for at least a couple of months, if not much longer.

Then, I bring them out whenever I make a sandwich, serve cheese or cold meats, or put together a salad. They are versatile and add a splash of color to any plate.You can use any vinegar you have on hand – white wine, red wine, or cider vinegar are all nice – but the balsamic gives the final product a slightly richer flavor and adds an extra kick of acidity to balance out the sweetness from the sugar. 

Ingredients

Balsamic vinegar pickled onions are one of my favorite appetizers to make and serve. They pair so well with so many dishes you can imagine that I like to keep them on hand at all times. Here's a list of the ingredients you need to make a batch of these delicious small bites:

• Red Onion: The key to this recipe is thinly slicing the onions, so they pickle quickly. You'll want to cut them relatively thin (⅛-inch thick or less), so you might need a sharp knife and some patience. Feel free to use a mandoline if you have one.
• Sugar
• Salt 
• Balsamic vinegar: a delicious variety of vinegar that originated in Modena, Italy
• Garlic Mustard Seeds: If you do not have garlic mustard seeds, feel free to use regular mustard seeds!

How to pickle red onions

Pickling red onions are an easy way to preserve them and make them last longer. In addition, it's a great way to add flavor to your food.

Slice the onions

Slice the onions into paper-thin rounds using a mandoline or a sharp knife. We like to use a mandolin slicer with a safety guard, making it easy to slice the onions. You could also cut them by hand. Slice them as thin as possible to pickle quickly.

Prepare the jar

Wash 1-quart glass jars and lid with hot soapy water and set aside to dry.

Make the balsamic vinegar brine

Combine balsamic vinegar, water, and salt in a saucepan over medium heat. Bring to a boil, occasionally stirring until the salt dissolves. Remove brine from heat and let cool to room temperature

Assemble

Pack the onion slices into your clean jar(s) until they are almost overflowing. Pour the brine, fill the jar, and cover all red onions. Tap the jar on your counter to eliminate any air bubbles and ensure that all onions are submerged in the brine.

Wait, then enjoy

Cover with a lid and let sit overnight at room temperature to pickle. The next day, transfer to your refrigerator and chill for 24 hours before using, as this will allow them to fully pickle. The pickled onions will keep in an airtight container in your refrigerator for up to 6 months!

Variations

There are quite a few ingredient lovers you can pour when creating your version of this recipe.

Switch up your onions: for instance, we decided to use red onions here, but white onions could be a nice swap out. Use what you have!

Swap in herbs and spices: Add in some spices that would fit with the balsamic vinegar to build on those delicious flavors. 

Vinegar: You can experiment with vinegar. Try apple cider vinegar, but I've also used red wine vinegar, white wine vinegar, and sherry vinegar, and all are good. I'm a fan of balsamic vinegar, so I'm very happy to let those flavors stand on their own but try what works for you. Feel free to use what you have on hand. 

Serving Suggestions

Balsamic vinegar pickled onions are delicious and can add a nice kick of flavor to almost any dish, from salads to pizza. There are many possible serving options for these brine-flavored onions. Take a look at some suggestions below.

Balsamic Vinegar Pickled Onions are a great addition to any sandwich, charcuterie board, or cheese plate. Serve them as a side dish with crackers or toasted baguette slices with some sliced feta. I personally like them with my eggs in the morning (they're sort of like pickled eggs but different), but that could be just me.

Storage

Store these in the fridge, ideally in a glass jar with a tight-fitting lid. The onions will keep for several weeks if stored correctly. The vinegar will not spoil until there is no longer any moisture left in the container, so you can leave it in your fridge without worrying about it going bad too quickly.
I usually make a jar at a time. These quick-pickled onions are great for serving alongside burgers, on top of pizza, or simply enjoying them on their own.

FAQs

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