Portobello Cheeseburger With Sweet Onion Relish

READY IN: 55mins
Recipe by WicklewoodWench

I created this for Ready Steady Cook and wanted to call it "Guilt Free Cheeseburger" because it is low carb and gluten free,,,but unless it's fat free and vegetarian it's not without sin. But then I never claimed to be completely virtuous. The relish can be made well in advance and can be stored in the fridge for up to a week. I love the flavour of chilli but I don't like the heat to overpower the taste so I have only used mild chilli flakes, however if you prefer you can increase the amount or even use a hotter chilli. *Only use the stalks of the mushrooms in the main meat mixture, the actual mushrooms are the bun.

Top Review by Susie D

I wanted to try this recipe as it caught my eye. However, I did make changes to fit the budget and items on hand. as the recipe had 5 other contest ingredients I used lean ground sirloin and skipped grinding my own. I also elected to serve the burgers on a crustini bun so only prepared one portabella cap per burger. All three compontents of the recipe are good, although the cooking times were off for me. The mushroom caps & burgers are full of flavor and the spicy sauce accents them nicely. I did like the dressed argula too. Served with Recipe #454925
Thank you for your entry & good luck in the contest! :-)

Ingredients Nutrition


  1. Preheat the oven to 425 degrees F.
  2. To make the relish; sauté the onions in the oil over a medium heat.
  3. When the onions have softened, approximately 10 mins, add the garlic and sauté for another ten mins, stirring occasionally.
  4. Add the chilli flakes, bbq and Worchester sauce mix and continue to cook on a medium heat for a further 5 minutes.
  5. Season to taste and set aside.
  6. Wipe clean the mushrooms of any debris(don't wash).
  7. Remove stalks and set aside for the burgers.
  8. Combine the oil and garlic together.
  9. Brush the mushrooms inside and out with the garlic oil (any remaining oil should be kept to dress the Arugula).
  10. Place the mushrooms CAP SIDE UP on a baking sheet and bake for about 20 to 25 minutes.
  11. Meanwhile, preheat the grill to hot.
  12. Place the steak in a food processer or mincer and process until finely minced.
  13. Place minced steak, chopped onion, mushroom, mustard, egg yolk, olive oil and seasoning in a large bowl and stir to combine.
  14. Using your hands, shape into four equal-sized patties, make a slight indentation in the centre of the patty And place about an ounce of cheese in the indent, bring the mixture around to cover the cheese and reflatten slightly ensuring all the cheese is covered. Repeat with the remaining patties.
  15. Cook the burgers under the grill for 15 minutes, or until cooked through, turning once.
  16. To assemble, place a mushroom CAP SIDE DOWN on a serving dish.
  17. Lightly dress the arugula in the garlic oil retained from the mushrooms, take a small handful and place on the mushroom.
  18. Add a burger, then relish and top with another burger CAP SIDE UP.
  19. Repeat with remaining burgers and serve hot with salad and fries.

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