There’s something about the smell of slowly caramelising onions that takes me right back to Sunday dinners at my mum’s — when every burner was going, the kitchen windows were fogged up, and someone was always yelling “Mind the gravy!” across the table. Lyonnaise potatoes were never the star, but they were the secret hero on the side. Golden edges, soft middles, and a tangle of sweet onions laced with butter and herbs — simple food, but when it’s done right… oof, it’s soul-lifting.
Now, this one’s got Mary Berry’s name on it — which basically means: no faff, everything works, and you’ll probably impress someone unintentionally. She keeps it classic — potatoes sliced just so, a bit of thyme (don’t skip it), and onions cooked so gently you could almost sing them a lullaby. It’s one of those dishes that rewards a bit of patience. Nothing flash. Just honest food that hugs your belly.
Why You’ll Love It
- Caramelised onions make the whole kitchen smell amazing (your neighbours will be jealous)
- The potatoes go crisp on top, soft underneath — best of both worlds
- It’s all made in one dish — great for fuss-free cleanup
- You can prep ahead and bake it when needed (hello, dinner parties)
- It’s vegetarian-friendly but hearty enough to stand on its own
- Leftovers? Even better fried up the next day with an egg on top
Ingredients
- 3 large onions, sliced
- 2 tbsp olive oil
- 50g (1¾oz) butter
- 1.2kg (2lb 12oz) medium potatoes (Desiree, Maris Piper, or Elfe), peeled
- 2 tbsp finely chopped flat-leaf parsley, plus more for serving
- 2 tbsp fresh thyme leaves, plus more for serving if you fancy
- 2 garlic cloves, thinly sliced
- Salt and freshly ground black pepper
How to Make It
Get the onions soft and sweet:
Grab your biggest pan and chuck in the sliced onions with the olive oil and half the butter. Let them cook low and slow — about 30–35 minutes — until they’re meltingly soft but not browned. Stir now and then, maybe sip a cuppa while they do their thing.
Boil the potatoes (just briefly!):
While the onions do their slow dance, bring a big pot of salted water to the boil. Slice the peeled potatoes into 1cm thick rounds. Once the water’s bubbling, tip them in and boil for 3 minutes — no more. Drain and let them steam-dry in the colander.
Infuse the onions:
Take your onion pan off the heat and stir in the sliced garlic, parsley, thyme, and a generous seasoning of salt and pepper. It’ll smell divine already. Try not to eat it with a spoon (guilty).
Combine and mix gently:
In a large mixing bowl — or the pan if it’s roomy — gently toss the parboiled potatoes with the herby onion mix. Don’t break them up too much, but get everything coated and evenly spread.
Layer it up:
Transfer everything into a deep-ish baking dish (no deeper than about 5cm/2in). Press down lightly with the back of a spoon to level it out. Dot the rest of the butter across the top like a buttery breadcrumb trail.
Into the oven we go:
Bake in a preheated oven at 200°C (180°C fan)/Gas 6 for 35–40 minutes, until the top is golden and crisp and the potatoes are cooked through. You can scatter on extra herbs if you’re feeling fancy — or don’t. It’s lovely either way.
Common Mistakes and How to Dodge Them
Why are my potatoes mushy?
You probably overboiled them — they only need a short parboil (3 minutes tops). They should still feel a bit firm when you drain them.
My onions burned — what went wrong?
Heat was too high. Keep it low and give them time. If they start to catch, a splash of water can help slow things down.
It’s bland — help?
Be bold with seasoning. Potatoes soak it up, and you need enough salt and pepper to lift the herbs and onions.
Confession time: I once forgot to drain the potatoes properly and ended up with a watery bottom layer. Lesson: steam-dry is not optional.
Storage and Reheating
Fridge: Pop leftovers into a sealed container — they’ll keep for up to 3 days.
Freezer: Yes, you can freeze it! Wrap tightly and store for up to 2 months. Defrost in the fridge overnight before reheating.
Microwave: Reheat a portion on a plate, covered, for 2–3 minutes.
Oven: Best method! Reheat in a hot oven (about 180°C/350°F) for 15–20 minutes until warmed through and crisp again.
Frequently Asked Questions
Can I make this ahead of time?
Absolutely. Assemble it all, cover, and stash it in the fridge. Just bake when you’re ready — might need a few extra minutes if cold.
Do I have to peel the potatoes?
Nope. If you like the skin (and the texture it brings), leave it on! Rustic and lovely.
Could I add cheese?
Sure — it’s not traditional, but a little grated gruyère or cheddar on top before baking wouldn’t hurt anyone.
Can I make this vegan?
Yep! Just swap butter for vegan butter or a bit more olive oil. Still delicious.
Nutrition Facts (Per Serving):
- Calories: 220
- Fat: 9g
- Carbs: 27g
- Protein: 6g
- Sodium: 300mg
- Sugar: 5g
Try More Mary Berry Recipes:
Mary Berry Lyonnaise Potatoes
Description
Crispy-edged, buttery Lyonnaise potatoes with sweet onions and herby flavour — a French-inspired side that steals the show.
Ingredients
Instructions
- Slowly cook onions with olive oil and half the butter for 30–35 minutes until soft.
- Parboil potato slices in salted water for 3 minutes; drain and steam-dry.
- Stir garlic, parsley, thyme, salt, and pepper into the onions.
- Combine onions and potatoes gently in a bowl.
- Transfer to a baking dish no deeper than 5cm.
- Dot with remaining butter.
- Bake at 200°C (180°C fan) for 35–40 minutes until crisp and golden.
Notes
- Don’t skip the parboil — it ensures tender insides and crispy tops.
- Always let the onions go fully soft before combining — rushed onions taste raw.
- A non-stick or ceramic dish works best for even browning.
- Steam-drying the potatoes is key — soggy ones lead to a watery bake.