Whole30 + Keto Marinated Onions Recipe + Video – a simple low carb, healthy fat macros side dish and marinade that adds tons of flavor to almost every recipe! Paleo, gluten free, grain free, dairy free, sugar free, clean eating, real food.

There are not adequate words to describe how much I love these Whole30 + Keto Marinated Onions. I was introduced to these by No Crumbs Left.

They have changed my world in the best way possible.

They make every meal more delicious! It is the condiment you never knew you needed that I serve alongside almost everything!

Whole30 + Keto Marinated Onion Ingredients

The onions are marinated for 12 hours in olive oil, red wine vinegar, dried oregano and salt. I’ve tweaked No Crumbs Left’s original recipe and added salt and even more red wine vinegar so they’re more of a marinated onion + pickled onion hybrid. The onions become bursting with flavor while mellowing their sharp bite. Absolutely addicting.

Bonus? The oil they marinate in becomes even more delicious and absorbs the onion flavor. It is my favorite oil to use as a meat marinade or to make salad dressings! I even drizzle it on top of cooked meats, seafood and vegetables. Such a flavorful and simple way to add healthy fat macros to your meals!

Marinated Onion Bowl

While you can make these in any size bowl, I highly recommend getting a Marinated Onion Bowl. It is the perfect size to fit the onions needed for this recipe, and the pour spout is perfect when you need to drizzle the marinated oil over meats or to make a salad dressing.

Teri has so many gorgeous pottery pieces available at her online store. All handmade with love. I think I have 1 of everything, ha! They make me so happy! Like she says, it’s jewelry for your kitchen!

Uses for the Marinated Onions

  • On top of salads
  • Serve alongside roasted or gilled meats, seafood and veggies
  • Use as a side dish to eggs, frittatas and omelettes
  • On top of tacos, burrito bowls

Uses for the Marinated Onion Oil

  • Use as a salad dressing! I’ll pour in 2 tablespoons of the marinated oil, then add in a pinch of salt, pinch of monk fruit, and dijon mustard. Whisk, taste and adjust seasoning as needed. My go-to salad dressing!
  • As a marinade for meats before roasting or grilling
  • Drizzled on top of cooked meats, seafood and vegetables to bring even more flavor
  • Use as a base to mayonnaise instead of avocado oil to make a flavorful aioli

Watch Marinated Onions Recipe Demo (3:52 minutes)

Whole30 + Keto Marinated Onions

Recipe heavily inspired by
, who is one of my favorite food bloggers to follow!
This Whole30 + Keto Marinated Onions Recipe is a simple low carb, healthy fat macros side dish and marinade that adds tons of flavor to almost every recipe!
5 from 15 ratings


  • 1 medium red onion, sliced 1/4" thick (I love using my mandoline)
  • 3/4 cup olive oil
  • 1/4 cup red wine vinegar
  • 1 tablespoon dried oregano
  • 1 teaspoon kosher salt


  • Place the sliced onions in a No Crumbs Left Marinated Onion Bowl. (I highly recommend getting a Marinated Onion Bowl! Holds the onions perfectly, has a pour spout so you can easily pour the onion marinade, and is such a gorgeous piece of pottery!)
  • In a measuring cup, combine the olive oil, red wine vinegar, oregano and salt. Stir to combine.
  • Pour the marinade over the onions. All the onions should be covered.
  • Let it sit on your counter for at least 12 hours.
  • Will keep for at least 5 days on the counter.


I don't recommend storing these in the refrigerator. The oil solidifies. If you're getting past the 5 days, you could store in a mason jar and refrigerate. You'll just have to bring them to room temperature when you want to eat them again.
These are really best with red onions, but you could use a yellow onion if that's all you have.
Dried oregano is much better than fresh oregano for these onions
You don't want to reuse the marinade. It gets too potent of an onion flavor. You'll want to start with a fresh marinade each time you make them.
Calories: 190, Total Carbs: 2.1g, Protein: 0.3g, Fat: 21g, Fiber: 0.5g, Net Carbs: 2g
Did you make this recipe?Please Leave a comment and give this recipe a rating!

Recipe heavily inspired by No Crumbs Left. This post contains affiliate links, thanks for the love!