Celeriac Gratin with Caramelised Onions

Over the summer I signed up to Local Greens - a not for profit weekly vegetable bag scheme providing seasonal veg from small organic or spray-free farms, which are as near to SE London as they can find.  To keep costs down, customers collect their bags from local pick up points (in Camberwell, Herne Hill and East Dulwich), rather than have them delivered to their door.  The idea is to use the minimum packaging and transportation so that they can pay the farmers a good price for their produce.  One benefit for me is that the veg has often been picked 24 hours or less before it makes it to my plate.

The majority of the ingredients in this recipe came from my Local Greens bag a couple of weeks ago and I bought some gorgeous golden rapeseed oil from Bambuni in Nunhead so this turned out to be a thoroughly locally sourced dinner!

It serves 2 hungry (greedy?) adults or a family of 3 or 4 if you reduce the amount of salt you use.  Perfect for an autumnal evening meal.

Ingredients

1 small celeriac

4-5 medium potatoes

3 cloves garlic (thinly sliced)

200ml single cream

Salt & freshly ground black pepper

Grated parmesan or other hard cheese (this is a good chance to use up any odds and ends lurking in the fridge)

For the caramelised onions:

2 tbsp rapeseed oil

2 onions (sliced)

3-4 sprigs thyme (leaves only)

1 tsp soft brown sugar

1 tsp good sherry vinegar

Method

Preheat the oven to 160C.

Peel and thinly slice the celeriac and potatoes (the easiest way to do this is in a food processor or using a mandolin, if you have either) and pop them straight into a bowl of cold water. Pat dry on a clean tea towel and then layer into a deep casserole dish, seasoning with salt and pepper and adding the garlic as you go. Pour the cream over the top and give the casserole dish a little shake to make sure it reaches the bottom layers. Sprinkle the cheese over the top (as much or as little as you like - I like a good layer!).

Pop into the oven for around 50 minutes to an hour, or until the potatoes and celeriac are cooked and browned on top.

Once the gratin is in the oven, put the oil and onions into a heavy based pan over a low heat. Cook the onions very slowly, stirring often, until they begin to turn golden brown (this will take around 30-40 minutes) and then add the sugar, thyme and season with salt and pepper. Cook for around another 5 minutes. Add the vinegar and cook until the liquid has disappeared. The onions should now be caramelised and a rich brown colour.

Serve the gratin with a spoonful of caramelised onions and a crisp green salad lightly dressed with sherry vinegar and cold pressed rapeseed oil.