This recipe was inspired by Dorie Greenspan's Mustard Tart. I first saw her recipe while reading The Baker's Apprentice column in the NYT and I was intrigued. I add dijon to a lot of recipes but I never thought of adding it to a tart. I quickly filed the recipe away and then just as quickly forgot about it. . .until this contest was announced. I took her recipe and ran with it.
I modified the crust by removing the sugar, adding semolina flour (inspired by Midge's cheddar apple pie), duck fat (inspired by a comment to Merrill's slow roasted duck), gruyere cheese and lots of herbs. I also modified the filling by swapping out the vegetables, adding more herbs and topping it with a little cheese. Whether you try this recipe or Dorie's original, I hope you enjoy it as much as we did. —melissav
one 9 inch tart
all purpose flour
unsalted butter, very cold, cut into small pieces
duck fat, very cold
egg, lightly mixed with a fork
Potatoes (small red) or fingerlings, sliced 1/8 inch thick - enough to make one slightly overlapping layer in the tart pan (like you would if making a apple tart). I used three medium red potatoes.
leaves of Rainbow Chard, stems minced and leaves rolled up and cut into a chiffonade
duck fat or olive oil
whole grain dijon
salt and pepper
gruyere cheese, very finely grated like on a microplane - measured fluffed - don't compact it
In This Recipe
Put the flours, salt, and herbs in the food processor and whiz to mix together. Add the butter, duck fat, and cheese and pulse until the butter and duck fat are coarsely incorporated - like little pebbles. Add half the egg and 1tsp of water and pulse. Add the rest of the egg and pulse. Check the dough to see if it holds together when pinched. If not, add the remaining water tsp by tsp until it does.
Dump onto a piece of saran wrap and gather into a ball. Wrap in the saran wrap and press into a disk. Refrigerate for a couple of hours or overnight or freeze for one hour.
Roll out. This is easiest if you do it between two pieces of saran wrap. Carefully remove one side of the saran wrap and lay it in a 9 inch tart pan with a removable bottom. Carefully press the dough into the bottom on the pan and then up the sides of the tart pan. Roll a rolling pin over the top of the pan to cut off the excess dough. Place in the freezer for at least 30 minutes or you can leave in the fridge for a few hours.
Preheat the oven to 400. When ready to bake, line the dough with foil, fill with pie weights or dried beans, place on a cookie sheet lined with a piece of foil and bake for 20 minutes. Remove from oven, remove foil with pie weights (you can save them for future use), and put back in the oven for 5-7 minutes until lightly golden.
Let cool before filling and baking. I put in the freezer for 20-30 minutes.
Preheat the oven to 425.
Melt the duck fat over medium low to medium heat in a non-stick skillet and add the potatoes, season with salt and pepper, and cook for 5-7 minutes. You don't want to cook the potatoes - you are just softening them a bit, seasoning them, and coating them in the duck fat. Remove to a small bowl.
Throw the chard stems in the skillet, cover for 3 minutes to soften and then add the chard leaves and scallions and cook for 5 minutes until softened. Taste and make sure well seasoned. Set aside.
Whisk together the eggs, cream, creme fraiche, mustards, and herbs. Season lightly with salt.
To assemble the tart, place the chard on top of the crust. Then arrange the potatoes in one slightly overlapping layer over the chard, pressing down lightly to compact the chard and potato layer. Slowly pour over the custard mixture.
Bake it for 20 minutes on the foil lined cookie sheet. After 20 minutes, pull out the oven shelf, sprinkle the cheese on top and bake for approximately 10 more minutes until lightly golden and a knife inserted in the middle comes out clean.
Let cool for 5 minutes on a wire rack and then remove the ring. It helps to place the tart on a small bowl and then slide the ring down. I like the tart best warm but not piping hot. The mustard flavor is muted a bit when the tart is too hot. You could also eat at room temp or cold if you prefer.