One of my favourite restaurants in New York is the Grand Central Oyster Bar. I've always found this place a bit incongrous, and those of you who have been there will know what I am talking about: it's a labyrinth of sparkling marble and mosaic tiled rooms, decorated in the Byzantine style, and built directly underneath the station, offering an extensive choice of oysters from every shore in the United States.
And with the oysters comes a spicy horseradish and tomato sauce (or ketchup), served up in those little paper cups. You'll also find this sauce in American diners. I've noticed that some Americans just call it "horseradish sauce", which is slightly confusing as it's red in colour, and quite clearly contains tomato; while here in Perfidious Albion, "horseradish sauce" is the creamy stuff we serve with the roast beef of Merry Old England. You say tomato, we say tomarto, let's call the whole thing off.
Here's a good (if slightly lengthy) way to make your own version. I've based it on Simon Hopkinson's wonderful book Week in Week Out, which is currently The Greasy Spoon's "Book of the Month". The secret lies in making both the horseradish concentrate and the tomato juice ahead of time, and then keeping both of them in the 'fridge. The horseradish concentrate can also be used for English style creamed horseradish sauce and delicious horseradish mousse. The homemade tomato juice can be used for mixing Bloody Mary's.
First you need to make a homemade horseradish concentrate: Grate 200g of peeled horseradish root into a food processor and add five tablespoons of water, two teaspoons of Maldon Salt, 1 ½ tablespoons of caster sugar, 2½ tablespoons of lemon juice and 2½ tablespoons of white wine vinegar. Make sure you peel the horseradish and then grate it across the base of the root. Whizz it up in the food processor until smooth, and then tip it into a Kilner jar (it should keep in the 'fridge for up to two weeks).
Next, you need to make a homemade tomato juice: take 1kg of very ripe tomatoes and core and cut them up into quarters. Put them in a large pan. Add a heaped teaspoon of Maldon Salt, a tablespoon of caster sugar, and 125ml of water. Cover the pan and warm on a lowish heat for about twenty minutes. You want the tomatoes to wilt. There should also be quite a bit of tomato juice floating around in the pan.
Pour the contents into a vegetable mill (mouli-légumes) and grind it up. (It's really worth investing in an authentic mouli-légumes, and I've included a link to buy one from amazon uk. It's a decent bit of kit and indispensable if you are going to make your own purées, sauces and soups.
Leave the tomato juice to cool, and stir in a tablespoon of horseradish concentrate. Let it infuse for about ten minutes and then pass the sauce through a sieve. That make's a basic tomato juice.
To make the ketchup: take 300ml of the tomato sauce and reduce it in a small pan, until it thickens up. Remove it from the heat, let it cool down and stir in two tablespoons of the horseradish concentrate. Chill in the 'fridge. Perfect with oysters.
