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Garlic-covered portobello mushroom on grilled rump steak with cauliflower mash and green beans on a white plate.

Grilled Rump Steak with Garlic Mushrooms and Cauliflower Mash

  • Author: Ella @myconvenientkitchen
  • Total Time: 45 minutes
  • Yield: 4 1x


Cauliflower mash is my absolute favourite side dish. Its outrageously good—creamy, silky, and punched up with earthy-umami goodness  and perfect with Grilled Rump Steak. It stacks up against the most loved comfort foods. Super customisable and incredibly delicious, it’s the essence of cozy warmth and happy flavours in every bite.


Units Scale
  1. 1 Cauliflower, cut into 2cm pieces, core included
  2. 160g Light cream cheese
  3. Salt and pepper, to taste
  4. 4 Portobello mushrooms, wiped clean
  5. 4 tbsp. Butter, softened
  6. 4 cloves of Garlic, peeled and crushed
  7. 1 tbsp. Fresh Rosemary, leaves removed from stem and finely chopped
  8. 280g Green beans, trimmed
  9. 2 tbsp. Olive oil
  10. 4 Thick Rump steaks


Preheat oven to 200°C/180°C fan-forced

Prepare the cauliflower:

  • See note 1
  • Prepare the cauliflower by cutting it into small, even-sized florets. 
  • Steam the cauliflower by placing it in a steamer over a large pot of boiling water, steaming for 15 minutes until tender. 
    (Alternatively, bring a large pot of salted water to a boil. Cook the cauliflower in the boiling water for 10-15 minutes or until very tender.)  
  • Once cooked, remove the cauliflower and thoroughly drain using a colander. To ensure optimal texture, use the back of a large spoon or ladle to press out all excess water – a crucial step in the process
  • Transfer the cauliflower to a food processor. Add the cream cheese and puree until completely smooth. For a chunkier texture, mash by hand. Season to taste and keep warm.

Prepare the mushrooms:

  • Meanwhile, place mushrooms on a baking tray, gill side up. 
  • In a small bowl, combine butter, garlic, rosemary and seasoning and mix until smooth. Use half of the mixer to top each mushroom evenly. Reserve the rest to baste the steaks.  Bake for 15 minutes or until cooked.

Prepare the green beans:

  • Steam green beans for 5 minutes or until just tender and season.

For the perfect grilled steak:

  • See note 2 
  • While the mushrooms are cooking, preheat your grill to high heat. 
  • Brush both sides of steak with oil. Add the beef to grill and cook for 2-3 minutes each side for medium-rare or until cooked to your liking. 
  • Baste the steak with butter on both sides in the last minutes of cooking.
  • Transfer to a cutting board rest for 5 minutes. 

To serve:

  • Divide the mash between warmed serving plates. Top with the steak (You can serve it whole or cut against the grain. Place a whole field mushroom on top of each piece of steak taking care to catch all the butter and juices. Serve with steamed green beans.


    Prepare the Cauliflower: Cut the cauliflower into EVENLY sized florets. Discard the tough stem. Rinse the florets thoroughly.
    Steam the Cauliflower: Steam the cauliflower, instead of boiling it in water. Steam until VERY TENDER. You can use a steamer basket on the stove or cook it in the microwave. The cauliflower should be easily pierced with a fork.
    Drain Excess Moisture: This is very important step and ensures a delicious texture. Drain any excess moisture from the steamed cauliflower. You can place the florets on a clean kitchen towel and gently press to remove excess water or follow instructions as per recipe.
    Prepare the Steak: Take the rump steak out of the refrigerator and let it come to room temperature for about 20-30 minutes. This ensures more even cooking.
    Preheat the Grill: Preheat your grill to high heat. The grill should be hot to ensure a good sear on the steak
    Season Well: When your steak is at room temperature and just before cooking, season the steak generously with salt and pepper on both sides. Don’t be shy with the seasoning.
    Brush with olive oil: Brush both sides of the steak with olive oil just before placing it on the grill. This helps prevent sticking and promotes a nice sear.
    Grill to perfection: Place the steak on the hot grill grates. For a medium-rare result, grill for about 2-3 minutes on each side. Adjust the time based on your preferred doneness and the thickness of the steak.
    Optional: Baste with Butter: For an extra touch of richness, you can optionally baste the steak with melted butter infused with garlic and herbs during the last minute of cooking.
    Rest the Steak: Remove the steak from the grill and let it rest on a cutting board for at least 5 minutes. This allows the juices to redistribute, ensuring a juicy steak.
    Serve whole or Sliced: Serve either whole for a stunning presentation or sliced against the grain for maximum tenderness. Plate it up, and you’re ready to enjoy your perfectly cooked rump steak!
  • Prep Time: 20
  • Cook Time: 25
  • Category: Main
  • Method: Grilling

Keywords: Rump steak, beef steak, mushroom, cauliflower mash