Potato and leek gratin

Potato and leek gratin combines tender layers of potatoes and aromatic leeks in a creamy sour cream sauce, baked to a golden finish. It's an ideal comforting side dish or main course.

28 Nov 2025
Cook time 80 min
Prep time 15 min

Ingredients:

1/3 cup butter
4 leeks
5 potatoes
2 cups light sour cream
2 garlic cloves
1/3 cup tarragon (estragon)

Potato and leek gratin is a classic French dish that's both comforting and flavorful. This recipe combines tender potatoes, aromatic leeks, and a creamy sauce, all baked until golden and bubbly. It's perfect as a side dish or even a main course.

Instructions:

1. Preheat the Oven:
- Preheat your oven to 375°F (190°C).
- Grease a large baking dish with a small amount of butter to prevent sticking.

2. Prepare the Leeks:
- Trim off the dark green parts of the leeks, keeping only the white and light green parts.
- Slice the leeks in half lengthwise, then rinse under cold water to remove any dirt or grit.
- Slice the leeks into thin rings.

3. Cook the Leeks:
- In a large skillet, melt the 1/3 cup (70g) of butter over medium heat.
- Add the sliced leeks and minced garlic to the skillet. Sauté until the leeks are soft and translucent, about 8-10 minutes. Season with salt and pepper to taste.
- Remove from heat and set aside.

4. Prepare the Potatoes:
- Peel the potatoes and slice them thinly, about 1/8 inch (3mm) thick, using a knife or mandoline.

5. Assemble the Gratin:
- In the greased baking dish, arrange a layer of potato slices, slightly overlapping.
- Spread a portion of the cooked leeks evenly over the potato layer.
- Spoon a portion of the light sour cream over the leeks, spreading evenly.
- Sprinkle a portion of the chopped tarragon over the sour cream.
- Repeat the layers (potatoes, leeks, sour cream, tarragon) until all ingredients are used, finishing with a layer of potatoes on top.

6. Bake:
- Cover the baking dish with aluminum foil.
- Place the gratin in the preheated oven and bake for 45 minutes.
- Remove the foil and continue baking for an additional 15-20 minutes, or until the top is golden brown and the potatoes are tender when pierced with a fork.

7. Serve:
- Remove from oven and let the gratin sit for a few minutes before serving.
- Cut into portions and serve warm.

By following these steps, you’ll have a deliciously creamy and flavorful potato and leek gratin that's sure to impress your family and friends. Serve it hot and enjoy the meld of tastes and textures in every bite.

Potato and leek gratin FAQ:

What is the ideal baking time for potato and leek gratin?

The gratin should be baked for a total of 60 to 65 minutes. Start by covering it with aluminum foil and baking for 45 minutes, then remove the foil and bake for an additional 15 to 20 minutes until the top is golden brown.

How can I tell if the potatoes are done?

The potatoes are done when they are tender and can be pierced easily with a fork. If they are still firm, continue baking for another 5-10 minutes and check again.

Can I substitute the light sour cream with another ingredient?

Yes, you can substitute light sour cream with Greek yogurt or regular sour cream for a richer flavor. Just keep in mind that using full-fat options may change the texture slightly.

How should I store leftovers of the gratin?

Leftovers should be cooled to room temperature and stored in an airtight container in the refrigerator for up to 3-4 days. Reheat in the oven or microwave before serving.

What size baking dish is recommended for this recipe?

A large baking dish, approximately 9x13 inches, is recommended to accommodate the layers of potatoes and leeks evenly. Make sure it's greased to prevent sticking.

Tips:

- Use a mandoline to slice the potatoes evenly and thinly, ensuring even cooking.

- Make sure to clean the leeks thoroughly as they tend to hold a lot of dirt between their layers.

- For extra flavor, you can sauté the garlic in the butter before adding the leeks.

- If you prefer a richer dish, you can substitute the light sour cream with heavy cream or a mix of cream and sour cream.

- Top the gratin with a layer of grated cheese, such as Gruyère or Parmesan, for an extra golden and crusty top.

- Let the gratin rest for a few minutes after baking to allow it to set before serving.

Nutrition per serving

6 Servings
Calories 420kcal
Protein 10g
Carbohydrates 54g
Fiber 6g
Sugar 6g
Fat 18g

Potato and leek gratin