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Caramelised Onion Sausage Burger and Cheesy Fondue Dip

Caramelised Onion Sausage Burger and Cheesy Fondue Dip

with Pommes Frites and Portobello Mushrooms
4.0(173)
Recipe Development Team
Recipe Development TeamUpdated on January 23, 2026
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Calories
1150 kcal
Protein
36.9g protein
Difficulty
Medium
Allergens:
  • Milk
  • Rye
  • Wheat
  • Barley
  • Cereals containing gluten
  • Egg
  • Sulphites
  • Mustard
  • Milk
  • May contain traces of allergens
  • Cereals containing gluten
  • Rye
  • Sesame
Produced in a facility that processes eggs, milk, fish, peanuts, sesame, shellfish, soy, tree nuts, and wheat.
serving amount

450 grams

Potatoes

2 unit(s)

Portobello Mushrooms

1 unit(s)

Onion

60 grams

Mature Cheddar Cheese

(Contains: Milk, May contain traces of allergens, Milk)

2 unit(s)

Burger Buns

(Contains: Cereals containing gluten, Rye, Sesame, May contain traces of allergens, Milk, Rye, Wheat, Barley, Cereals containing gluten, Egg)

75 grams

Creme Fraiche

(Contains: Milk)

10 grams

Dijon Mustard

(Contains: Sulphites, Mustard)

225 grams

British Pork and Oregano Sausage Meat

(Contains: Wheat, Cereals containing gluten, Sulphites)

25 grams

Sun-Dried Tomato Paste

20 grams

Wild Rocket

Not included in your delivery

1 tsp

Sugar

10 grams

Butter for the Sauce

1 tbsp

Plain Flour

100 milliliter(s)

Water for the Sauce

2 tbsp

Mayonnaise

Energy (kJ)4810 kJ
Energy (kcal)1150 kcal
Fat63.6 g
of which saturates27 g
Carbohydrate106.4 g
of which sugars20 g
Dietary Fibre10.9 g
Protein36.9 g
Salt4 g
Potassium1432 mg
Calcium282.3 mg
Iron1.3 mg
Always refer to the product label for the most accurate ingredient and allergen information.
Baking Tray
Pan
Bowl
Grater
Small sauce pan

Instructions

Make your Frites
1

Preheat your oven to 220°C/200°C fan/gas mark 7.

Chop the potatoes lengthways into 1cm slices, then chop into 1cm wide chips (no need to peel) to make your pommes frites.

Pop the chips onto a large baking tray. Drizzle with oil, season with salt and pepper, then toss to coat. Spread out in a single layer. TIP: Use two baking trays if necessary.

When the oven is hot, bake on the top shelf until golden, 25-30 mins. Turn halfway through.

In the meantime, remove the stems from the portobello mushrooms and pop them onto a baking tray, cut-side up. Drizzle with oil and season with salt and pepper.

Caramelise the Onion
2

Roast the portobellos on the middle shelf until tender, 18-20 mins. Once cooked, carefully drain any excess liquid from the portobello mushrooms.

Meanwhile, halve, peel and thinly slice the onion.

Heat a drizzle of oil in a large frying pan on medium heat. Once hot, add the onion, season with salt and pepper and fry, stirring occasionally, until golden, 10-12 mins.

Stir in the sugar (see pantry for amount) and cook until caramelised, 1-2 mins more.

Once cooked, remove from the heat and set aside for later.

Make your Fondue Dip
3

Add the sausage meat to a large bowl. Season with pepper and mix together with your hands.

Roll into even-sized balls, then shape into 1cm thick burgers, 1 per person. TIP: The burgers will shrink a little during cooking. IMPORTANT: Wash your hands and equipment after handling raw mince.

Pop the burgers onto a baking tray. Bake on the middle shelf until cooked through, 12-15 mins. IMPORTANT: The burgers are cooked when no longer pink in the middle.

While everything cooks, grate the Cheddar. Halve the burger buns.

Heat the butter (see pantry for amount) in a small saucepan until melted, sprinkle over the flour (see pantry for amount) and cook on a low heat, stirring frequently, for 1-2 mins - you've made a roux!

Gradually pour in the water for the sauce (see pantry for amount), stirring constantly, until there are no lumps, 3-4 mins. 

Finish the Prep
4

Increase the heat of the pan to medium, then stir in the creme fraiche, Cheddar and Dijon mustard.

Season generously with salt and pepper. Cook until the sauce has thickened and the cheese is melted, 2-3 mins.

Season generously with pepper again and remove from the heat. Add a splash of water if the sauce looks too thick.

Taste and season with more salt and pepper if needed. 

Warm the Buns
5

In a small bowl, mix the sun-dried tomato paste and mayo (see pantry for amount).

Just before you're ready to serve, pop the buns into the oven to warm through, 2-3 mins.

Reheat the fondue sauce if needed, then pour into small dipping bowls.

Finish and Serve
6

Share the bun bases between your plates and spread over the sun-dried mayo (see pantry for amount). Add a handful of rocket, then top with the sausage burgers and portobello mushrooms, stem-side up.

Spoon the caramelised onions over the mushrooms and sandwich shut with the bun lid

Serve the pommes frites and the fondue sauce alongside for dipping. 

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