Slow cooked beef pie with celeriac rosti crust

I made this for supper tonight, and can say it is one of the best things I've tasted in a long time. It's from his new book 'Eat'. I don't have the book, but came across the recipe the other day online, and typically I can't find out where now! So what follows is a close approximation to the recipe - all the correct ingredients, this is how I did mine: Heat a little oil in a pan and add in cubed stewing steak, brown over a medium heat, then add in a couple of spoons of flour, three chopped carrots, one chopped large parsnip and some stock. Leave to simmer for a while, then when the vegetables are starting to get tender, assemble the crust - grate 2/3 of a large celeriac root coarsely, add in some grated fresh horseradish to taste and melted butter to bind it.  Put the meat mixture into your pie dish, top with the rosti mixture and bake in the oven.  I had mine with buttered cabbage. Give it a try, it really is a winner.