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Portobello Mushroom, Halloumi & Sticky Onion Burger

Portobello Mushroom, Halloumi & Sticky Onion Burger

with Herby Fries & Truffle Mayo
5.0(2)
Recipe Development Team
Recipe Development TeamUpdated on February 20, 2026
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Calories
866 kcal
Protein
38.1g protein
Total
30 minutes
Difficulty
Easy
Allergens:
  • Eggs
  • Gluten
  • Milk
  • Soy
  • Wheat
  • May contain traces of allergens
  • Almond
  • Brazil nut
  • Cashew
  • Hazelnut
  • Macadamia
  • Peanuts
  • Pecan
  • Pine nut
  • Pistachio
  • Sesame
  • Sulphites
  • Walnut
Produced in a facility that processes eggs, milk, fish, peanuts, sesame, shellfish, soy, tree nuts, and wheat.
Serving amount

1 sachet

Garlic & Herb Seasoning

2

Burger Bun

(Contains: Eggs, Gluten, Milk, Soy, Wheat; May be present: Almond, Brazil nut, Cashew, Hazelnut, Macadamia, Peanuts, Pecan, Pine nut, Pistachio, Sesame, Sulphites, Walnut)

1 packet

Italian Truffle Mayonnaise

(Contains: Wheat, Gluten, Eggs; )

1

Red Onion

1 packet

Shredded Cheddar Cheese

(Contains: Milk; )

2 packet

Potato

1 packet

baby spinach & rocket mix

1

Portobello Mushrooms

1 sachet

Thyme

1 packet

Halloumi

(Contains: Milk; )

Not included in your delivery

1 drizzle

olive oil

1 tbs

balsamic vinegar

1 tsp

brown sugar

1 drizzle

vinegar (balsamic or white wine)

Calories866 kcal
Energy (kJ)3620 kJ
Fat52.1 g
of which saturates26.1 g
Carbohydrate61.3 g
of which sugars15.1 g
Dietary Fibre6.3 g
Protein38.1 g
Sodium1830 mg
Due to the different suppliers we purchase our products from, nutritional facts per meal can vary from the website to what is received in the delivered box, depending on your region.
Large Non-Stick Pan
Baking Paper

Cooking Steps

Bake the fries
1

• Preheat oven to 240°C/220°C fan-forced. Cut potato into fries. • Place on a lined oven tray. Drizzle with olive oil, season with salt and toss to coat. • Spread out evenly, then bake until tender, 20-25 minutes.

Make the caramelised onion
2

• While the fries are cooking, thinly slice onion (see ingredients). • In a large frying pan, heat a drizzle of olive oil over medium-high heat. Cook onion, stirring, until softened, 5-6 minutes. • Reduce heat to medium. Add the balsamic vinegar, brown sugar and a splash of water and mix well. Cook until dark and sticky, 3-5 minutes. Transfer to a small bowl.

Prep the mushrooms
3
  • Remove the stems from portobello mushrooms.
  • Cut halloumi into 1cm-thick slices.
Cook the mushrooms & halloumi
4
  • Wipe out the frying pan, then return to medium-high heat, with a drizzle of olive oil. 
  • Cook mushrooms, turning occasionally, until softened and most of the water has evaporated, 10-12 minutes. Transfer to a plate lined with paper towel. 
  • Return frying pan to medium-high heat with a drizzle of olive oil.
  • Cook halloumi until golden brown, 1-2 minutes each side. Transfer to a paper towel-lined plate.

TIP: Gently press down on the mushrooms with the back of a spatula to squeeze out excess water. 

Heat the buns & toss the salad
5

• Halve burger buns and bake directly on a wire oven rack until heated through, 2-3 minutes. • Thinly slice cucumber. • In a medium bowl, combine a drizzle of olive oil and vinegar. Add spinach & rocket mix and cucumber, season to taste and toss to coat.

Finish & serve
6

• Spread the bun bases with Italian truffle mayonnaise. • Top with portobello mushroom, halloumi, some caramelised onion and cucumber salad. • Serve with fries and remaining cucumber salad. Enjoy!

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