Potato Gratin

Ingredients

• 1.5 kgsmall potatoes
• 6 tbspolive oil
• 1 largeyellow onion
• 5 clovesgarlic
• 5 stalksfresh thyme
• 4 tbspplain flour
• 1 can or 400 mlcoconut milk
• 370 mlcashew milk or almond milk
• zest of 1/2lemon
• 2 tbspnutritional yeast
• 2–3 tspsea salt flakes
• a pinchfreshly ground pepper

Instructions

1. 1

   Wash potatoes

   Wash and scrub the potatoes thoroughly, since the skins will stay on.

2. 2

   Slice potatoes

   Use a mandoline or the slicing blade of a food processor to slice the potatoes. Put all the slices into a large ovenproof dish.

3. 3

   Cook aromatics

   Warm a frying pan over medium heat and add 2 tbsp of the olive oil. Finely chop the onion and sauté it for about 2 minutes. Slice the garlic, strip the thyme leaves from their stems and add both to the pan; sauté for about 2 more minutes, then add the mixture to the potatoes.

4. 4

   Preheat oven

   Preheat the oven to 200°C.

5. 5

   Make the sauce

   Heat a clean frying pan and add the remaining 4 tbsp of olive oil. When the oil is very hot, add the flour and stir until the two form a paste. Add the coconut milk and stir, then pour in the almond or cashew milk. Keep stirring until the mixture begins to thicken.

6. 6

   Season sauce

   Stir in the lemon zest, nutritional yeast, salt and pepper once the sauce starts to thicken. Taste it and adjust the salt, pepper or nutritional yeast if needed.

7. 7

   Coat potatoes

   Pour about three-quarters of the sauce over the potatoes and mix until the slices are evenly coated. Pour the remaining sauce over the top.

8. 8

   Bake gratin

   Put the dish in the oven and bake for about 40 minutes.

What is potato gratin?

Potato gratin is a dish of sliced potatoes baked in a rich sauce, associated with French gratin cooking. The top and edges bake while the potatoes soften and absorb the liquid.

This version uses olive oil, coconut milk and cashew or almond milk instead of dairy. Onion, garlic, thyme, lemon zest and nutritional yeast give the sauce plenty of savoury character.

Nutrition and macros by portion

The nutrition label shows one serving as written: 500 calories, 8g protein, 70g carbs, 23g fat.

Most of the carbohydrates come from the potatoes and flour, while olive oil and coconut milk contribute much of the fat. The potatoes, nut milk and nutritional yeast provide some protein, though this is mainly a carbohydrate- and fat-led dish. Pair a portion with greens and a protein-rich accompaniment such as beans to make a more balanced plate.

Keep the skins on

Scrub well: the recipe leaves the potato skins in place, so remove any soil before slicing. Small potatoes are easy to handle and their slices can be arranged throughout the dish.

Slice evenly: a mandoline or food processor helps make slices of a similar thickness, so they cook at roughly the same rate.

Build flavour before baking

Soften the onion: a short sauté takes away its raw bite and starts the flavour base. Add the garlic and thyme for the final couple of minutes so they become fragrant without prolonged cooking.

Season the sauce: lemon zest and nutritional yeast bring brightness and savouriness, while salt and pepper round it out. Taste before pouring, as this is the best chance to adjust the seasoning evenly.

Get a smooth sauce

Start with the paste: stir the flour into hot olive oil until it forms a smooth mixture. Add the coconut milk and then the nut milk, stirring as you pour to help prevent lumps.

Watch for thickening: keep stirring and look for the sauce to become noticeably thicker before adding the flavourings. It should still be pourable enough to coat the potato slices.

Coat every slice

Mix first: use about three-quarters of the sauce to coat the potatoes and aromatics, separating slices gently so the sauce reaches through the dish.

Finish on top: pour the remaining sauce over the surface. This gives the upper layer extra coverage as the gratin bakes.

Check the bake

The recipe gives a baking time of about 40 minutes at 200°C. Check the centre with a knife: it should pass through the potatoes without much resistance.

If the potatoes are still firm, continue baking and check again shortly afterwards. Allow the dish to settle briefly before serving so portions are easier to lift.

What to serve with it

Serve the gratin with a crisp green salad or steamed greens to bring freshness alongside its creamy, substantial texture.

It also works as a side for roasted vegetables or a plant-based main. Keep other rich sides simple so the potato dish remains the focus.

Recipe notes & tips

• Scrub the potatoes carefully before slicing, as their skins are left on.
• Slice the potatoes evenly so they soften at a similar pace.
• Stir constantly as you add the milks to the flour-and-oil paste.
• Taste the sauce before adding it to the potatoes and adjust the seasoning then.
• Check the centre of the dish with a knife before taking it out of the oven.

Variations

• Use one nut milk: choose either cashew milk or almond milk, as the recipe allows.
• Add extra herbs: increase the thyme slightly for a more pronounced herbal note.
• Brighten the finish: add a little more lemon zest to the sauce.
• Add greens: serve with steamed spinach or green beans alongside the gratin.
• Change the seasoning: add a pinch of smoked paprika to the sauce for a gentle smoky note.

Common mistakes to avoid

• Uneven slices: thick pieces may stay firm while thinner ones soften; aim for slices of similar thickness.
• Lumpy sauce: adding the milk too quickly can make the flour mixture clump; pour gradually and keep stirring.
• Under-seasoned sauce: taste it before combining with the potatoes and adjust the salt and pepper.
• Dry patches: mix the potatoes with most of the sauce before pouring the rest over the top.
• Taking it out too soon: if a knife meets firm potatoes in the centre, continue baking and check again.

How to store

Cool leftovers, cover and refrigerate for up to 3 days. Reheat in an ovenproof dish at 180°C until hot throughout; cover loosely if the top is browning too quickly.

Frequently asked questions