I have been loving this copycat In-N-Out sauce! It’s surprisingly easy, no blender is needed, and it’s the perfect addition to burgers and ground beef recipes.
Why You’ll Love This In-N-Out Sauce
- It tastes like the real thing. And possibly better, because you know exactly what’s in it and can adjust it to your taste.
- There’s just five ingredients. This sauce comes together in one bowl with a quick stir. It’s a simple blend of mayo, ketchup, sweet pickle relish, vinegar, and salt. There is NO mustard in it (as In-N-Out doesn’t have mustard in theirs).
- It’s make-ahead friendly. The flavors deepen as it sits in the fridge, so it’s actually better on day two.
In-N-Out is one of the few places I’ll stop for a quick “healthy-ish” bite. Many of you know that I’m a SoCal girl, so my love for In-N-Out runs deep.
And while I’ve been gluten-free for over a decade, which rules out most fast food, a protein-style double double burger with freshly cooked fries is one of my rare fast food exceptions. But it’s the sauce that makes the burger!
So when the sweet potato burger bowl started making the rounds on social media, I knew exactly what I wanted to drizzle on top: a homemade version of In-N-Out’s spread. I’d been wanting to crack the recipe for years anyway, and this was finally the excuse I needed.
The thing I love about In-N-Out’s spread is that it’s actually SO simple. It’s really just a well-balanced Thousand Island-style sauce, but the ratios matter. Too much ketchup and it’s overly sweet. Too much relish, and it gets watery. The white vinegar is the piece most copycat recipes miss entirely, and it’s what gives the real version its bright, slightly sharp finish!
What’s In the Sauce
- Mayonnaise: I use my homemade mayonnaise when I have it, but a good quality store-bought version works just fine here. Just grab one with a neutral flavor.
- Ketchup: This adds sweetness and that familiar tangy-tomato backbone. Three tablespoons is the sweet spot. Any more and it’ll be too sweet.
- Sweet pickle relish: This is the texture detail that matters. And because sweet pickle relish already has sugar added to it, there’s no need for any additional sugar. Alternatively, you could finely chop up dill pickles, then add your favorite sweetener.
- White vinegar and salt: This is what gives the sauce its bright and sharp finish. So don’t skip it!
Lisa’s Ingredient Note: Notice what’s missing from other copycat recipes? Mustard! While In-N-Out doesn’t publish exactly what’s in their spread, they’ve released allergen info that doesn’t include it. Their spread is also pale pink, not yellow-ish, and with a slightly sweeter, not sharper flavor profile… which all indicate mustard is not added.
Find the printable recipe with measurements in the recipe card below.
How To Make In-N-Out Copycat Sauce
Step 1: Make the sauce. Add the mayonnaise, ketchup, sweet pickle relish, white vinegar, and salt to a small mixing bowl. Stir together until completely combined and smooth.
Step 2: Use or store. Use immediately, or transfer to a sealed jar and refrigerate. If you have even 30 minutes before serving, let the sauce rest in the fridge. The last time I did, the flavor tasted even better!
Storage tip: This sauce keeps in the fridge for 5 to 6 days in a sealed jar. Give it a quick stir before each use.
How I Use This Sauce
I originally developed this sauce specifically to drizzle over my sweet potato burger bowl. I’ve been leaning into roasted sweet potatoes hard lately because I genuinely feel good after eating them, and pairing them with ground beef for protein just makes sense. The bowl needed a sauce, and this one fit perfectly: a little creamy, a little tangy, and totally nostalgic.
But then I made it again for a homemade lettuce wrap burger, piled high with all the fixings, and realized this sauce needs a permanent spot in my rotation. It’s the kind of condiment that makes everything taste better!
More Homemade Sauces
- Chipotle Sauce: Smoky and spicy!
- Tartar Sauce: Perfect paired with fish.
- Galic Aioli: A must-have for veggies and burgers.
- Horseradish Sauce: Best with anything beef.
If you make this copycat sauce, I’d love to hear what you put it on in the comment box below! Your review helps other readers in the community. And for more healthy food inspiration, join my free newsletter.
Description
Video
Ingredients
- ½ cup mayonnaise
- 3 tablespoons ketchup
- 2 tablespoons sweet pickle relish, chopped extra fine
- 1 tablespoon white vinegar
- pinch kosher salt
Instructions
- Make the sauce. In a small mixing bowl, add the mayonnaise, ketchup, sweet pickle relish, white vinegar, and salt. Stir together.
- Use or store. Use the sauce on burgers, fries, wraps, or as a dipping sauce. If not using right away, store it in the fridge and let the flavors meld together further. It's a great make-ahead sauce!
Lisa’s Tips
- Storage: This sauce keeps in the fridge for 5 to 6 days in a sealed jar. Give it a quick stir before each use.
- Yield: This recipe makes about ¾ cup of sauce, which is roughly 6 servings at 1½ tablespoons per burger or bowl.
Nutrition
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How I Recipe Tested This
I ate a LOT of In-N-Out burgers! 🤣 But seriously, I got extra sauce from my local In-N-Out location and then compared it to what I had in my mixing bowl. I kept tweaking the ratios until I felt it was a 100% perfect match for flavor, color, and texture. And ta-da, there you have it!
Love the flavor of this! It puts Russian Dressing to shame! It’s going to be my go-to from now on.
Wonderful! So happy you loved it!
OH EM GEE! This really does taste just like In N Out! I’m so excited to have this in my fridge now. Thanks Lisa!
Yay, I’m so thrilled you loved it, Kay!
Hi! Have you found a healthy sweet pickle relish store bought or do you make your own?
Hi Donna – I use a store-bought version. Though you could always quickly chop up some dill pickles as well. Enjoy!
This sauce sounds delicious and very similar to the British Prawn Cocktail Sauce recipe except with added sweet pickle. (Although the Brits do add double cream, sherry and lemon juice to the mix, instead of vinegar).
However, you say it keeps in the fridge for 5 days or so. This recipe will keep for much longer than that because it has vinegar in it. Vinegar is a preservative. Tomato ketchup doesn’t need to be stored in a fridge due to its high vinegar and sugar content. A bottle of Mayo alone will keep in the fridge for more than a year.
I never understand why recipes I read online, which include vinegar and sugar, are said to only keep a few days. It does not make any sense.
Hi Shelly – That’s a great question! While vinegar does help preserve foods, homemade sauces aren’t the same as commercially bottled products. Store-bought ketchup and mayonnaise are made under tightly controlled conditions and are formulated for a much longer shelf life (often through preservatives and heat processing). Since this is a homemade mayo-based sauce that’s been mixed and handled in a home kitchen, I recommend a conservative 5-day storage time for the best quality and food safety. But if you feel it’s still good after 5-days, you can always use your best judgement.