Beetroot, Potato & Horseradish Gratin

One of the best comfort foods on Earth is a creamy potato gratin dauphinoise. Thin slices of potato baked with garlic, nutmeg and cream is pretty much unbeatable. But we often mix the potato with other root veg or squashes, depending on what’s in season. (French people look away now!) Here’s one of our favourite variations with beautiful beetroots and fiery horseradish. Do you make variations of dauphinoise? What’s your best combo?

So what do you eat gratin with? It’s traditionally a side dish to go with meat and we often have a gratin in place of roast potatoes as part of our Sunday dinner. But it’s special enough to be the main event and we often just pair it with some simple steamed greens and a hearty lentil salad. Rich, soft and creamy meets fresh, crunchy and tangy!

Liz x

Ingredients (serves 4-6)

I have deliberately put approximations here as a gratin is a very fluid thing and the amounts depend on the texture of the vegetables as they cook, the size and depth of your roasting dish etc. Making a gratin is very forgiving too so just go by eye with amounts. You want to make enough to fill a medium roasting dish, the vegetables will shrink as they cook.

  • potatoes – approx 5 medium sized, scrubbed
  • beetroot – approx 5 medium-large, peeled
  • olive oil – approx 6 tbsp
  • garlic – 2 cloves, peeled
  • salt and pepper – to taste (I used 2 tsp salt and 1 tsp pepper)
  • oat milk – approx 250ml
  • nutritional yeast – approx 6 tbsp
  • fresh grated horseradish (or horseradish sauce) – to taste, I used about 4 tbsp fresh grated

Method

  1. Pre heat the oven to 180C. Find a deep, medium roasting dish and some tin foil (or a casserole dish with a lid).
  2. Thinly slice your potatoes and beetroots using a food processor, mandolin or a large, sharp knife. Try and keep the slices an even thickness, ideally around 3-4 mm thick. Put the slices in two separate bowls or mix them up in a large bowl, depending on if you would like to make layers or not.
  3. Divide the oil and seasoning between the bowls, then using a fine grater, grate the garlic over the vegetables too. Using your hands, mix the oil and seasoning evenly throughout the sliced vegetables.
  4. Layer the vegetables as you like. Mixed up or in neat layers, whatever you fancy! If you want separate colours, start with the beetroot then top with the potatoes. If the beetroot goes on top then all the colour will seep into the potatoes as they cook, which is fine too of course. Cover the dish with tin foil or a lid and place in the oven to bake until soft throughout. This usually takes about an hour and a half depending on the size and depth of your dish. Insert a small knife or skewer to test if the veg are done, there should be no resistance.
  5. Meanwhile mix the oat milk, nutritional yeast (this will enrich the milk and give it a savoury, creamy flavour) and grated horseradish. Horseradish looses it’s potency a fair bit as it cooks so it’s better to add it at this stage rather than at the beginning.
  6. When the vegetables are soft remove the lid/foil and pour over the milky mixture. You want to be careful here not to cover the vegetables, the liquid should stay below the top layer, otherwise your gratin will be a bit loose and not stick together nicely. Return to the oven without the lid and bake for another 15 minutes or until the gratin is hot through and starting to brown on top.
  7. Remove from the oven and let it sit for 5 minutes or so to set. Then slice or serve in scoops and enjoy!