Caramelised Onion & Sun-Dried Tomato Veggie Burger and Cheesy Fondue Dip
with Pommes Frites and Portobello Mushrooms
- Milk
- Cereals containing gluten
- Wheat
- Sulphites
- Mustard
- Soya
- May contain traces of allergens
- Egg
- Milk
- Soya
- Wheat
- Cereals containing gluten
Caramelised onions, mushrooms and homemade fondue cheese sauce give French inspired flavour to this tasty vegetarian burger. Served up with pommes frites, this is a taste of summer at home.
Ingredients
450 grams
Potatoes
2 unit(s)
Portobello Mushrooms
1 unit(s)
Onion
60 grams
Mature Cheddar Cheese
(Contains: Milk)
2 unit(s)
Burger Buns
(Contains: Cereals containing gluten, Wheat, May contain traces of allergens, Egg, Milk, Soya)
75 grams
Creme Fraiche
(Contains: Milk)
10 grams
Dijon Mustard
(Contains: Sulphites, Mustard)
2 unit(s)
Unconventional Plant-Based Burgers
(Contains: Soya, May contain traces of allergens, Wheat, Cereals containing gluten)
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
Nutritional information
Utensils
Instructions
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.
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.
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.
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 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.
When the potatoes have 6-8 mins left, place the veggie burgers on a lightly oiled baking tray.
Bake on the middle shelf until browned, 6-7 mins. IMPORTANT: Ensure they're piping hot throughout
Meanwhile, in a small bowl mix together 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.
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 veggie 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.
Enjoy!
Customer reviews
Review summary
Updated on Feb 2026- Flavour: Many enjoyed the burger's taste, though some found the fondue sauce bland or too mustardy.
- Ease of prep: Several noted considerable preparation time, with mixed opinions on whether the effort was worthwhile.
- Suggestions: Consider reducing mustard in the fondue; some preferred adding the cheese directly to the burger instead.
- Portions: One whole onion may be too much for two servings; adjust quantity to preference.
- Texture: For crispier chips, some customers recommend using their own cooking method.
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