Australian Wagyu Sirloin Filet with Fondant Potatoes and Veggies

Australian Wagyu Sirloin Filet with Fondant Potatoes and Veggies

By Nicholas Fiorentino

Australian Wagyu will elevate any dinner menu, but when it’s paired with buttery fondant (melting) potatoes and perfectly charred vegetables, you have a five-star restaurant quality meal right in your kitchen. For this recipe, we love to use a sous vide method for the steaks, where food is sealed in an airtight bag and cooked in a precisely controlled water bath. It guarantees a juicy steak with minimal effort every time. Try out this recipe for your next date night at home.


For steaks

  • 2 Australian Wagyu Sirloin Filets resting at room temp (BMS5 or above preferred)
  • 3 fresh thyme leaves or 1 ½  tsp of dried thyme
  • 1 clove of garlic (peeled)
  • ½ cup butter (unsalted)
  • Truffle salt and fresh ground pepper

For potatoes fondant

  • 2 large russet potatoes
  • 3 tbsp Rendered wagyu or duck fat or any other oil with high smoke point 
  • 3 cups chicken stock
  • 3 cloves of garlic (Peeled)
  • 1 fresh thyme sprig or ½ tsp of dried thyme
  • Salt and pepper to taste


  • 6-8 whole organic carrots (peeled)
  • 1 tbsp olive oil
  • Salt and pepper to taste


  • 1 tbsp butter
  • 1 tbsp olive oil
  • 1 clove of garlic
  • ⅓ cup water
  • 1 lemon


For Australian Wagyu:

Place the steaks in separate vacuum bags so that the water bath will cover all sides of the steaks. Slice up a clove of garlic into thin slices, and add 2-3 thyme leaves to the bags. Seal each bag, and place them in the sous vide for 2 hours at 110 degrees. After 2 hours, you can remove the bags from the water bath, and immediately place them into ice water to stop the cooking process. 

Now, take the steaks and other contents out of the bags. Using a cast iron pan on high heat (350 degrees), put the steaks in and sear on both sides. Once there is a good crust, lower the heat and add the remaining contents of the bags to the pan. Add another 2 tbsp of butter and baste the steaks as it melts. Remove the steaks when they reach an internal temperature of 120 degrees. Allow them to rest before serving in slices.

**If you don’t have a sous vide machine, you can cook your steaks in the oven at 225 until the internal temperature has reached 110 degrees instead.

For Potatoes:

Preheat the oven to 425 degrees. Slice the Yukon Golds into 1 inch thick slices that are flat on two sides. Heat a cast iron skillet and add ¼” of oil to the bottom of the pan using wagyu or duck fat (or oil of your choice). Then, place the potatoes on the pan and sear them broad side down without moving them until they begin to brown around the edges and easily release from the pan. When they're a deep golden brown, flip them over and add a generous amount of butter. This produces a great sear on the first side, and then starts the process of building the braising sauce. Thyme and crushed garlic cloves go in next to infuse the butter, for a buttery taste. Frying is only the first step, the hard part is the stock that makes the potatoes creamy.

Plain stock will not give you the texture you want so be it chicken or beef stock, you will need to add unflavored gelatin to get a creamy texture.  Add enough stock to submerge the potatoes as they will soak up a good amount of the stock and the rest will make a spoon-coating sauce. Now cover the pan and place it in the oven for 30 minutes or until the chicken stock is completely reduced. 

Once the potatoes are fully tender, remove them to a serving platter and finish the sauce on the stovetop, adding a little more stock if needed to achieve a smooth emulsion. 

For Carrots:

Clean and peel your carrots and place them on a cookie sheet lined with parchment paper (avoid stacking them on each other). Lightly coat the carrots with olive oil and sprinkle with salt and pepper. Place the cookie sheet in the oven at 425 degrees. Let the carrots cook for 10 minutes, then rotate them, and let them cook for another 10 minutes or until they are lightly charred. After around 20 minutes, you can remove them from the oven and serve.

For Broccolini:

Trim the stalks of your broccolini to your liking and set aside. Heat a pan over medium-high heat, and add 1 tbsp of butter and olive oil. Put the broccolini in the pan with a sliced clove of garlic and toss until everything is coated. Add in ⅓  cup of water and cover the pot until the water evaporates. Season with salt and place 1 or 2 lemon slices in the pan. Increase the heat until there is a light sear on the vegetables. Remove from heat and serve.

In conclusion, this recipe might look involved, but it can always be simplified for each individual person. Try out what works for you, and you’ll be surprised that a meal like this can be made right from your kitchen!

Search Recipes

shop nick’s favorite cuts

Shop All