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–+ servings

Hachis Parmentier

Dinner
Lentils du Puy simmered with a classic mirepoix of onion, carrot, and celery, thyme, bay leaf, and a touch of tomato concentrate until rich and deeply savoury, then topped with a generous layer of buttery mashed potato and a blanket of Gruyère, gratiné until golden. This vegetarian hachis parmentier is the sort of dish that makes you want to eat straight from the pan, ideally with a good glass of red.
Hachis Parmentier recipe
Prep Time 20 minutes
Cook Time 55 minutes
Servings 4

Ingredients 

For the lentil filling
For the mashed potato topping
To finish

Equipment

Instructions

  1. 1. Cook the lentils du Puy
    Rinse the lentils under cold water. Unlike many other lentils, lentils du Puy don't need soaking, and crucially they hold their shape through cooking, which is exactly what you want here. Put them in a saucepan, cover with cold water, bring to the boil, and cook for 20 minutes until just tender but still with some bite. Drain and set aside. Don't salt the water during cooking, as it toughens the skins.
  2. 2. Build the filling
    Set your braisier over a medium heat on the hob and add the olive oil. Add the onion, carrot, and celery chopped as "mirepoix" (small cubes) and cook gently for 10 minutes, stirring occasionally, until softened and starting to turn golden. Add the garlic and cook for another 2 minutes.
    Stir in the tomato concentrate and cook for a further 2 minutes, letting it caramelise slightly against the base of the pan. This is where a lot of the flavour comes from, so don't rush it. Pour in the vegetable stock and add the thyme and bay leaves. Season well with salt and pepper.
    Add the drained lentils and simmer everything together over a medium-low heat for 15–20 minutes until the stock has reduced down to a rich, cohesive sauce that clings to the lentils rather than sitting around them. The filling needs to hold its shape under the mash. Stir in the red wine vinegar, taste, and adjust the seasoning. Remove the thyme sprigs and bay leaves. Take the braisier off the heat.
  3. 3. Make the mash
    While the lentils are simmering, cook or steam the potatoes in well-salted boiling water for 20 minutes until completely tender. Drain thoroughly and leave to steam-dry in the colander for a couple of minutes, excess moisture makes for a sloppy mash and you don't want that sitting on top of the lentils.
    Pass the potatoes through a ricer back into the pan, or mash until completely smooth. Beat in the butter until melted and fully incorporated, then add the warm milk and crème fraîche. Season generously with salt, white pepper, and freshly grated nutmeg. The mash should be smooth, rich, and loose enough to spread easily but not runny.
  4. 4. Top, finish, and bake
    Preheat the oven to 200°C / 180°C fan. Spoon the mashed potato directly over the lentil filling in the braisier and spread it carefully to the edges, covering everything completely. Use a fork to create ridges across the surface, this gives you more texture and more crispy bits. Scatter the grated Gruyère evenly over the top.
    Transfer the braisier to the oven and bake for 25 minutes until the cheese is melted and golden and the edges are starting to bubble. For a properly golden top, finish under the grill for 3–4 minutes. Keep an eye on it.
  5. 5. Rest and serve
    Leave it to rest for 5 minutes before serving, the filling will be extremely hot and needs a moment to settle. Bring the braisier straight to the table and serve directly from it with a simple green salad dressed with a sharp mustard vinaigrette on the side.

Notes

  • Lentils du Puy specifically is what makes this work. They hold their shape through cooking and have a mineral, earthy flavour that generic green lentils simply can't match. Look for the AOP label if you can find it.
  • Don't rush the mirepoix. Ten minutes of gentle cooking builds the flavour base the whole dish rests on. If the vegetables go in barely softened, the filling will taste flat.
  • The tomato concentrate is there as background, not as a feature. Two tablespoons is enough to add depth and a little colour without announcing itself. This dish is about the lentils.
  • A wide, shallow braisier works better here than a deep casserole. You want a good ratio of mash to filling in each spoonful, and a deeper dish throws that off. The wider the better for the gratin on top too.
  • Make ahead: build the whole thing up to the baking stage, leave to cool, and refrigerate for up to 24 hours. Take it out of the fridge 30 minutes before baking and add 10 minutes to the oven time.
  • Leftovers keep well in the fridge for 2–3 days and reheat brilliantly in the oven at 180°C for 20 minutes, covered with foil.
  • Comté works just as well as Gruyère on top, and arguably better, it has a slightly nuttier, more complex flavour that's worth trying if you can find it.