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Burger with Blue Cheese, roasted onions & mustard sauce

Burger with Blue Cheese, roasted onions & mustard sauce

4 servings

Our recipe for incredible blue cheese burgers with mustard sauce and roasted onions perfectly melds complimentary intense flavours. Resting on a bedding of fresh lettuce, tomatoes and pickles, mouth-watering beef patties enjoy a layer of rich blue cheese and spicy mustard sauce.

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  • 4 slices of Castello® Burger blue
  • 4 burger buns
  • 450 g beef mince
  • salt
  • ground pepper
  • 2 red onions, in thick slices
  • 4 green lettuce leaves
  • 2 tomatoes, sliced
  • 4 whole pickles

Mustard sauce:

  • 250 ml sweet mustard, such as French’s
  • 4 tbsp acacia honey
  • 50 ml apple apple cider vinegar
  • 2 tbsp red chillies, finely chopped
  • 2 tbsp tomato ketchup
  • 2 tsp worcestershire sauce
  • ½ tsp garlic powder
  • ground black pepper
  • fries or potatoes wedges
  • fresh thyme for sprinkling



1. Combine all the ingredients for the mustard sauce and refrigerate for a few of hours – preferably overnight.

2. Roast the onion slices until blackened on a very hot and dry pan. Divide them into onion rings and set aside.

3. Form the meat into 4 patties and season with salt and pepper.

4. Heat a grill pan until it is smoking hot. Fry the patties for about 3 minutes on each side – set them aside to rest.

5. Split the buns and warm or toast them. Place the cheese on the patties and spread the buns with mustard sauce, then top the buns with lettuce, patties, roasted onions and tomatoes.

6. Finish with the top bun and serve with pickles, fries with a sprinkle of thyme and extra mustard sauce.