Ultimate Grilled Chicken

grilled chicken with mustard sauce

We’re elevating our grilled chicken by pairing it with the most amazing sauce filled with the toasted sweetness of caramelized onions, bright tanginess of mustard, and richness of the creamy sauce. This Ultimate Grilled Chicken recipe is sure to impress!

grilled chicken with creamy mustard sauce on plate with broccoli and wild rice

How to Make Grilled Chicken with Creamy Mustard Sauce

This recipe seems a bit more involved, but it’s really very simple. Start with the onions, which take the longest amount of time to cook. While the onions cook on the stovetop, heat your grill to medium high and prep your chicken by patting it dry and seasoning it with salt and pepper.

Grill your chicken for 5-10 minutes per side or until the internal temperature reaches 165 degrees F. The time it will take depends on the thickness of your chicken. Always cook to the proper temperature regardless of the time it takes!

Technique: Caramelizing Onions

You want to caramelize these onions so they become golden brown and a bit sweet. The perfect contrast to the sharpness of mustard in the sauce. To do this, you want to cook them low and slow in butter with a sprinkle of salt. Stir them occasionally so they cook evenly and don’t burn.

Watch them turn a beautiful golden brown. This will take around 30 minutes. Don’t be tempted to try to speed the process by turning up the heat! If you do, you will end up with burnt onions and butter, which definitely do not make for a tasty sauce. 

We love the traditional method, used here, but are also intrigued by this method from America’s Test Kitchen, a known and trusted source of food knowledge. Check it out and let us know if you try it!

Caramelizing your onions ahead of time makes this dish weeknight-friendly. Once caramelized, you onions will keep for 2-3 days in a tightly-sealed container in the refrigerator. Simply let them cool to room temperature before refrigerating them. When you are ready to grill your chicken, warm your onions over low heat before continuing with your sauce.

close up of grilled chicken with creamy mustard sauce

Technique: Thickening Your Sauce

Add minced garlic to the caramelized onions and cook for just a minute. Then we thicken the sauce with a roux, which is simply fat and flour cooked briefly then whisked with liquid. In this case, we have butter for the fat and chicken stock for the liquid. 

Of course, there’s a ratio for this! I love learning ratios because knowing the right balance of ingredients allows you to create your own variations. In this case, knowing this technique and ratio will allow you to make a perfectly thickened sauce any time, even without a recipe right in front of you. (Want to learn more about this long-standing and super useful technique? Check out this article by Serious Eats!)

To thicken eight ounces (one cup) of liquid, you will need one tablespoon of fat and one tablespoon of flour. Heat the fat, stir in the flour and cook for one minute, then whisk vigorously while slowly pouring in your liquid.

For our sauce, we already have the butter in the pan. Once the garlic is fragrant, add the flour and stir for one minute. This cooks out the raw flour taste so it doesn’t show up in your sauce. But don’t cook the flour for too long or it will lose its thickening power. Slowly pour in the chicken stock while whisking the lumps out of the flour. Yes, you will get onions stuck in your whisk. It’s okay. Just keep going! 

Turn up the heat and bring the mixture to a simmer. Watch it thicken while you continue to stir. Once that happens, remove it from the heat and stir in the remaining sauce ingredients, including the yogurt, mustard, and vinegar for bright tanginess.

Trouble-Shooting Your Sauce Technique

Our sauce here is pretty straightforward. If your sauce doesn’t thicken, there are a couple of things that could have happened.

  • There wasn’t enough butter remaining in the pan. If you notice this, simply melt some more butter before adding your flour.
  • The flour cooked for too long. Make sure you only cook it for about a minute. If you lose track of time, add a bit more flour.

If you are faced with a thin sauce, you can still serve it and it will still be delicious! You can try to thicken it by re-making the roux (the butter and flour) in a separate pot. Whisk in a little of the liquid from your original sauce. Then whisk the new roux into your original pan.

Serving Your Grilled Chicken with Creamy Mustard Sauce

Once your chicken is cooked to temp, allow it to rest on a plate or serving platter at room temperature for 10 minutes. This can happen while you finish your sauce. When your sauce is done, pour it over your chicken on a platter, then serve!

This really is the ultimate grilled chicken recipe! A simple salad makes for the perfect side dish. Try one of these amazing options!

Don’t Forget Dessert!

Of course, no meal is really complete without a sweet treat. Everything in moderation, right? Here are some perfect desserts to serve with with your grilled chicken.


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grilled chicken with creamy mustard sauce

The Ultimate Grilled Chicken with Creamy Mustard Sauce

We’re elevating grilled chicken by pairing it with the most amazing creamy sauce filled with caramelized onions and tangy mustard.
Prep Time 10 minutes
Cook Time 40 minutes
Course Chicken Dish, Grilled, Main
Cuisine American
Servings 4 people


  • 1 tablespoon olive oil
  • 1 tablespoon butter
  • 1 medium onion sliced
  • 4 boneless skinless chicken breasts about 1-1/2 pounds
  • 2 cloves garlic minced
  • 2 tablespoons flour
  • 1 cup chicken broth
  • 1/2 teaspoon coarse kosher salt or 1/4 teaspoon table salt
  • 1/4 teaspoon ground black pepper
  • 1 tablespoon dijon mustard
  • 1 tablespoon plain yogurt regular or Greek
  • 1-1/2 teaspoon white wine vinegar


  • Prep: Preheat your grill to medium-high.
  • Caramelize Your Onions: Heat the olive oil and butter in a skillet over low heat. Add the onion slices, sprinkle with a pinch of salt, and cook for 30 minutes, stirring occasionally. They will turn dark golden brown in color.
  • Grill Your Chicken: While the onion cooks, prepare your chicken by patting it dry and sprinkling with a pinch each of salt and pepper. Grill the chicken over medium-high heat for 5-10 minutes per side, or until it reaches an internal temperature of 165 degrees F. Remove the chicken from the grill to a serving platter, then loosely tent with foil and set aside to rest.
  • Finish Your Sauce: When the onions are dark caramel brown, add the minced garlic to the pan and cook for 30 seconds, stirring constantly. Stir in the flour and cook for one more minute before slowly whisking in the broth. Raise the heat to medium and stir, scraping the browned bits off the bottom of the pan, until the sauce thickens. When it is thick enough to coat the back of a spoon, remove it from the heat and stir in the salt, pepper, mustard, yogurt, and vinegar.
  • Serve: Pour your sauce over your chicken and serve.


  • You can caramelize your onions ahead of time. When they are browned, let them cool to room temperature before refrigerating them in an airtight container for up to 3 days. Rewarm them in a skillet over low heat with a little bit of butter before adding the garlic and finishing the sauce as directed in the recipe.
  • The time it will take your chicken to cook depends on the thickness. If your chicken is around 1/2 inch thick, it will take closer to 5 minutes per side; if your chicken is an inch or more in thickness, it will take longer and may take more than 10 minutes. Always cook to the stated temperature, even if it takes longer than the stated time.
Keyword caramelized onions, chicken, grilled, mustard sauce
Tag @mealtimejoy on instagram if you made this recipe

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