I discovered pickled red onions by accident at a taco place in Mile End. The guy behind the counter piled these bright pink onions on my carnitas tacos, and I remember thinking they looked too pretty to be that good. One bite changed everything. They were sweet, tangy, crunchy, and somehow made the rich pork taste even better. I asked him what they were, and he just shrugged and said “pickled onions, super easy to make.”
The next week, I made my first batch before a date came over for tacos. When she took a bite, she pointed at the onions and said “where did you get these?” I told her I made them, and she looked at me like I had just revealed some secret cooking superpower. The truth is they take about 15 minutes of actual work, but nobody needs to know that.
Quick Overview
- Prep time: 10 minutes
- Cook time: 5 minutes
- Total time: 1 hour 15 minutes
- Servings: 6
- Difficulty: Easy
Why You’ll Love These Pickled Red Onions
Makes you look like a way better cook. Rice vinegar and aromatics create complex flavor. Sweet, tangy, slightly herbal. Raw red onions are harsh. Pickling makes them mellow and bright. Fennel seeds add subtle licorice. Peppercorns give gentle heat. Thyme brings earthiness. Incredibly versatile. Works on tacos, burgers, cheese plates. Pink color is stunning. Makes any dish look professional. Costs almost nothing. Takes barely any effort. Elevates your cooking seriously.
Ingredients for Pickled Red Onions
Main Ingredients
- 1 red onion (about 150 g)
- 240 ml rice wine vinegar (1 cup)
- 240 ml water (1 cup)
- 3 g salt (1/2 tsp)
- 1 g black peppercorns (1/4 tsp)
- 1 g fennel seeds (1/4 tsp)
- 1 bay leaf
- 1 sprig fresh thyme
Ingredient Notes
Rice wine vinegar is milder than white vinegar, which is why these onions taste sweet and balanced instead of harsh. You can find it at any grocery store in Montreal, usually near the soy sauce.
For the onion, look for firm red onions with tight, papery skin. Avoid ones that feel soft or have green shoots growing out the top.
Fresh thyme is better than dried for this recipe. If you can only find dried, use about 1/4 tsp instead of a whole sprig.
Substitutions
- Can’t find rice vinegar? Use white wine vinegar or apple cider vinegar (but the flavor will be sharper)
- No fennel seeds? Use a pinch of crushed coriander seeds
- No fresh thyme? Use a small pinch of dried thyme or oregano
Step-by-Step Instructions
Step 1: Slice the Onion
Peel the red onion and slice it as thin as you can, about 2mm thick. I aim for thin strips that are almost see-through. The thinner they are, the faster they pickle and the better the texture. Put the sliced onions in a heat-safe bowl.
Step 2: Boil the Pickling Liquid
In a small saucepan, combine the rice vinegar and water. Bring it to a rolling boil over medium-high heat. This takes about 3-4 minutes.
Step 3: Add the Aromatics
Once the liquid is boiling, add the salt, peppercorns, fennel seeds, bay leaf, and thyme sprig. Let everything boil together for 5 minutes. Here’s the science: boiling extracts the essential oils and flavors from the aromatics and infuses them into the pickling liquid. The heat also helps dissolve the salt completely.
Step 4: Pour Over Onions
Carefully pour the hot pickling liquid over the sliced onions. Make sure the onions are completely submerged. If they’re floating, use a small plate or weight to keep them under the liquid. The hot liquid will soften the onions slightly and start the pickling process immediately.
Step 5: Let Them Sit
Let the bowl sit at room temperature for at least 1 hour. The onions will turn bright pink as they pickle. After an hour, they’re ready to use, but they get even better after a few hours in the fridge.
Expert Tips for Perfect Pickled Onions
Slice Them Thin
Thin slices pickle faster and have better texture. If your slices are too thick, they’ll stay crunchy in a way that’s not pleasant.
Keep Them Submerged
Onions that stick out of the liquid won’t pickle properly and can turn brown. Keep everything under the brine.
Don’t Skip the Aromatics
The fennel, peppercorns, bay leaf, and thyme are what make these special. Without them, you just have onions in vinegar.
Make Them Ahead
These are perfect to make in the morning for dinner that night, or even the day before. The flavor improves with time.
What to Serve with Pickled Red Onions
Tacos and Burritos
These are essential on any taco. They cut through the richness of meat and cheese perfectly.
Burgers and Sandwiches
Pile them on burgers, pulled pork sandwiches, or even grilled cheese. They add brightness and crunch.
Grain Bowls
Top rice bowls, quinoa bowls, or salads with these for color and tang.
Cheese and Charcuterie Boards
Add them to a cheese plate for something bright and acidic between bites of rich cheese.
FAQs About Pickled Red Onions
How long do pickled red onions last?
They’ll keep in the fridge for up to 2 weeks in an airtight container. Keep them submerged in the pickling liquid.
Why did my onions turn pink?
Red onions contain anthocyanins, which react with acid and turn bright pink. This is normal and desirable.
Can I reuse the pickling liquid?
You can use it once more for a second batch, but the flavor will be weaker. Fresh liquid is better.
Can I use white or yellow onions?
You can, but they won’t turn pink and the flavor will be sharper. Red onions are best for this recipe.
Do I need to refrigerate them?
After the initial hour at room temperature, yes, store them in the fridge. They’re quick pickles, not shelf-stable.
Recipe Card: Herbed Pickled Red Onion Recipe
Description: Sweet, tangy pickled onions with fennel and thyme. Ready in just 1 hour.
- Prep Time: 10 minutes
- Cook Time: 5 minutes
- Total Time: 1 hour 15 minutes
- Servings: 6
- Difficulty: Easy
Ingredients
- 1 red onion (150 g), thinly sliced
- 240 ml rice wine vinegar
- 240 ml water
- 3 g salt (1/2 tsp)
- 1 g black peppercorns (1/4 tsp)
- 1 g fennel seeds (1/4 tsp)
- 1 bay leaf
- 1 sprig fresh thyme
Instructions
- Slice red onion as thin as possible and place in a heat-safe bowl
- Boil rice vinegar and water in a saucepan
- Add salt, peppercorns, fennel seeds, bay leaf, and thyme to boiling liquid
- Boil for 5 minutes to infuse flavors
- Pour hot liquid over onions, making sure they’re submerged
- Let sit at room temperature for 1 hour before serving
Pro Tips
- Slice onions thin for best texture
- Keep onions submerged in liquid
- Make ahead for better flavor
- Store in the fridge for up to 2 weeks
Storage
Refrigerate in an airtight container for up to 2 weeks.
