In And Out Fry Sauce Recipe: West Coast Fast Food Favorite

There’s something about West Coast fast food that just hits different. This sauce brings that iconic flavor straight to your kitchen.

It’s quick to mix up and even quicker to disappear—perfect for fries, burgers, or anything that needs a creamy, tangy kick.

Ingredients for In and Out Fry Sauce

Nine simple ingredients blend into that signature West Coast tang you crave instantly.

The mayo is doing most of the heavy lifting here—Hellmann’s or Best Foods are the gold standard. Grab them at any grocery store, but I always keep a backup jar in the pantry. Ketchup and mustard balance the creaminess, so don’t skimp on quality. Heinz ketchup and French’s mustard hit that fast-food vibe perfectly. The relish adds sweetness and texture (sweet works best, but dill’s fine too).

No sweet relish? Chopped bread-and-butter pickles get you close. Out of paprika? Smoked paprika at half the amount adds a little extra depth. Want it spicier? Dash of cayenne or hot sauce does the trick. If you’re avoiding sugar, swap the relish for sugar-free pickle relish—works like a charm. The vinegar keeps it fresh, but lemon juice works in a pinch.

This keeps for 1 week in the fridge in a sealed jar. The flavors meld after a day, so it’s actually better the next time. Freezes for up to 3 months too, but honestly, it never lasts that long here.

Step-by-Step Instructions for In And Out Fry Sauce

This method takes less than 5 minutes and yields that signature West Coast flavor.

Step 1: Combine the Base Ingredients

In a medium bowl, add the 0.5 cup Mayonnaise and 0.25 cup Ketchup. I use a silicone spatula to scrape every last bit from the measuring cups—this ensures no flavor gets left behind. The mayonnaise should be full-fat for that classic creamy texture.

Whisk the two together until completely smooth and uniform in color. You’re building the foundation of your sauce here, so make sure there are no streaks of either ingredient visible. This usually takes about 20-30 seconds of vigorous whisking.

Step 2: Add the Tangy and Sweet Elements

Next, stir in the 2 tbsp Yellow Mustard, 2 tbsp Sweet Relish, and 1 tsp White Vinegar. I add these all at once because they balance each other perfectly—the mustard brings sharpness, the relish adds sweetness, and the vinegar provides that essential tang.

Mix for another 20 seconds until everything is fully incorporated. You’ll notice the color lighten slightly as the relish distributes throughout. The mixture should look slightly speckled from the relish but otherwise uniform.

Step 3: Season with Spices and Finish

Now add the 0.5 tsp Garlic Powder, 0.5 tsp Onion Powder, 0.25 tsp Paprika, and 0.25 tsp Salt. These dry ingredients need a final thorough mixing—another 20-30 seconds should do it.

Taste and adjust if needed, though I find this ratio hits that perfect In-N-Out balance every time. The paprika adds just a hint of smokiness without overpowering, while the garlic and onion powders create that subtle depth of flavor.

Step 4: Chill and Let Flavors Meld

Transfer the sauce to an airtight container. While you could use it immediately, I recommend letting it chill in the refrigerator for at least 30 minutes. This resting time allows all the flavors to marry together properly.

The sauce will thicken slightly as it chills, reaching that perfect pourable consistency. It keeps well for up to 5 days in the fridge, though I doubt it’ll last that long once you taste how good it is on fries or burgers.

Creative Variations of This in and out fry sauce

Spicy Kick Variation

Add ½ tsp cayenne pepper or a dash of hot sauce to the base mix for a little heat. I love using Tabasco or Cholula for this—they blend in perfectly without changing the texture. Start with ¼ tsp and adjust to your spice preference. 🌶️

Smoky Depth Upgrade

Swap regular paprika for ½ tsp smoked paprika. This adds a subtle BBQ-like flavor that works wonderfully with burgers and fries. For even more smokiness, try 1 tsp liquid smoke—just a drop makes a big difference.

Sweet and Tangy Twist

Replace the sweet relish with 3 tbsp finely chopped bread-and-butter pickles. Their sweet-tangy flavor gives the sauce a unique crunch. If you prefer a smoother texture, blend the pickles before adding. I’ve also used pickle juice for extra tang.

Herb-Infused Version

Stir in 1 tsp dried dill or 1 tbsp fresh chives at the end for a fresh herbal note. This variation tastes amazing with grilled chicken or fish. The herbs add a bright, garden-fresh flavor that balances the creaminess.

Creamier Option

For an extra-rich version, add 2 tbsp sour cream to the base. This makes the sauce thicker and even more luxurious. It’s perfect for dipping thicker cuts like sweet potato fries or onion rings.

Lighter Alternative

Use Greek yogurt instead of mayo for a tangier, lower-fat version. The texture is slightly thinner but still delicious. Add 1 tsp sugar to balance the extra tang from the yogurt. 💡

Frequently Asked Questions