Garlic Butter Steak with Fried Onion Strings and Mashed Potatoes Recipe

AdapTable Meals Garlic Butter Sirloin Steak served with savory mashed potatoes and crispy fried onion strings.

This post is sponsored by AdapTable ® Meals

Garlic Butter Steak with Fried Onion Strings and Mashed Potatoes Recipe

Is there anything better than steak and potatoes!? Yes, grilled garlic butter sirloin steak with creamy mashed potatoes and crispy fried onion strings. Thanks to AdapTable Meals, this fancy but fuss-free dinner is made easy by taking the main course entirely off your plate…no pun intended.

Adaptable Meals offers a wide array of pre-seasoned, pre-packaged meats that just need to be cooked and served. No additional prep is needed, making them a delicious and convenient timesaver in the kitchen. AdapTable Meals garlic butter sirloin steaks are seriously packed with so much flavor and pair really nicely with crispy fried onion strings and buttery mashed potatoes. It’s a winning combo that I’m really excited to share with you.

Adaptable Meals meats are gluten-free, a great source of protein, and made with ZERO artificial ingredients.

Meal prep with AdapTable Meals Sirloin Steak

Crispy Fried Onion Strings

Onion strings are great on burgers and of course, steaks. They’re honestly really easy to make and add an undeniable flavorful crunch to any dish. The only trick in terms of prep is to make sure you VERY thinly slice the onions so they melt in your mouth. We aren’t looking for onion rings here.

The process consists of soaking sliced onions in buttermilk for an hour to tenderize, dredging in flour and spices, and frying until golden and crunchy. The onions can be prepped ahead of everything else and can rest while you’re preparing other things. This will help take some stress out of juggling multiple items.

Golden Mashed Potatoes

If you’ve ever struggled with lumpy or gritty mashed potatoes, you’re likely missing one of the steps below. These mashed potatoes are really simple and come together with just butter, cream, milk, and a little garlic powder. With any mashed potatoes, it’s important to follow my tips below.


  • Always start the potatoes in cold water. If you add the potatoes directly to hot or boiling water, the outside of the potato will overcook before the inside is fully cooked. This can make your potatoes lumpy or gritty.
  • Cooking the potatoes in salted water enhances the flavor of your mashed potatoes. Failure to do so is the number one reason for bland potatoes. The potatoes will absorb the salted water and take on all of the seasoning. Use a generous amount of salt so you can actually taste it in the water. It’s much more difficult to season potatoes after they’ve already been cooked.
  • Don’t boil potatoes whole. Peel and cut potatoes into smaller chunks so they cook more quickly and evenly. They’re also easier to mash with your basic potato masher.
  • Cook until potatoes are fork-tender. They’re ready when a fork passes through the potato without any resistance at all. Yukon gold potatoes take about 25-30 minutes. It’s important to not undercook.
  • Always add warm or room temp butter and warm milk/cream. Cold ingredients will prevent the starches from absorbing the fats. I add the cream cheese last once the milk and cream have been fully mixed and the potatoes are smooth with no lumps.

Temperature for Steak

A digital thermometer is always going to yield the most consistent results. I’ve included grilling times in the recipe below, but when in doubt, always use a thermometer to check the temperature of your steak before removing it from the heat. Lastly, always let your steak rest for 5 minutes before serving!

Garlic Butter Steak with Fried Onion Strings and Mashed Potatoes Recipe

Trust me when I say these sirloin steaks are very flavorful and shouldn’t need any additional salt or spices to deliver delicious flavor. I highly encourage you to taste your finished steaks before adding additional seasonings.

DonenessTemperature Range
Very Rare/rare120°F to 125°F
Medium rare125°F to 130°F
Medium135°F to 140°F
Medium well145°F to 150°F
Well done160°F and above

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Garlic Butter Steak with Fried Onion Strings and Mashed Potatoes Recipe

  • Author: Shawn Williams
  • Prep Time: 15
  • Cook Time: 25
  • Total Time: 40 minutes
  • Yield: 2 1x
  • Category: Dinner
  • Cuisine: American



Mashed Potatoes

  • 1 1/2 pounds Yukon gold potatoes, peeled and quartered lengthwise
  • 1/3 cup heavy cream or half and half (warm)
  • 3 tablespoons butter (melted)
  • 1/2 teaspoon garlic powder
  • 1/2 teaspoon salt

Fried Onion Strings

  • 1 medium yellow onion, halved
  • 1 cup buttermilk
  • 1 cup all-purpose flour
  • 1/2 tablespoon salt
  • 2 teaspoons cayenne pepper
  • Pinch garlic powder
  • Canola oil, for frying


  1. For the onion strings: Cut the onion in half and very thinly slice into small half rings. Place the onions in a small bowl and submerge in buttermilk. Half an onion is enough for two servings. Let soak for 1 hour on the counter.
  2. Add flour, salt, and cayenne pepper to a separate bowl and mix. Bring oil to 375°F in a small saucepan. 1-2 inches of oil is all you need.
  3. Using tongs, remove the onion from the buttermilk and add to the bowl with flour mixture. Dredge until onions are fully coated. Remove from the flour, shaking off any excess, and add to saucepan with the oil. Fry for 30 seconds-1 minute or until onions are just starting to turn golden brown. Remove from the oil and place on a paper-towel-lined plate to drain.
  4. For the mashed potatoes: Add potatoes to a large pot. Fill the pot with cold water, covering the potatoes by at least 1 inch. Add a generous pinch of salt and bring to a boil, cover, and reduce heat to a simmer. Cook for 25-30 minutes or until potatoes can be EASILY pierced with a fork with no resistance.
  5. Drain water from the pot and add melted butter and warm cream. I warm butter/cream in short intervals in the microwave. Add garlic powder and mash until potatoes are creamy and smooth. Use a wooden spoon or whisk to stir out any remaining lumps. Add additional salt and pepper to taste as needed. Cover, and set aside. If the potatoes are too thick, add a splash of cream or milk.
  6. For the steaks: Preheat the grill to medium-high heat and clean the grates well.
  7. Place the steaks face down and sear undisturbed for 5 minutes. Flip and sear for an additional 5 minutes. This is ideal for medium-rare.
  8. For rare, sear for 4 minutes a side. Medium rare, 5 minutes. Medium, 6-7 minutes. Medium well, 8+ minutes. Remember, depending on the size of the steak, the more or less time it will take. When in doubt, use a digital thermometer.
  9. Serve steaks topped with crispy onion rings and a side of mashed potatoes. Garnish with optional minced parsley.


Temperatures for steak Rare: 120°F to 125°F Medium rare: 125°F to 130°F Medium: 135°F to 140°F Medium well: 145°F to 150°F Well done: 160°F and above.

The sirloin steaks are adequately salted and seasoned and really require nothing more than throwing on the grill. Taste before adding additional seasoning or flavors.

The fried onion strings can be made first and be set aside until ready to serve. No need to juggle everything at once.


  • Serving Size: 1 steak (no sides)
  • Calories: 250
  • Sugar: 1g
  • Sodium: 710mg
  • Fat: 10g
  • Saturated Fat: 3.5g
  • Trans Fat: 0g
  • Carbohydrates: 2g
  • Fiber: 0g
  • Protein: 36g
  • Cholesterol: `00mg

Keywords: steak with crispy onions, garlic butter steak, sirloin steak, steak and mashed potatoes, fried onion strings