Roasted Roots & Flamingo Pea Pie

Method

For the Pastry

1. Place the flour, butter, and salt into the bowl of a freestanding mixer. Using the paddle beater, mix on a medium speed until the mix resembles fine breadcrumbs. Add the egg yolk and tablespoon of water, then continue to mix until a cohesive dough begins to form (only about 30 seconds — stop immediately when it does), adding the second tablespoon of water if needed.
2. Remove from the bowl and bring the dough fully together with your hands. Divide it into two discs, one about 1.5x bigger than the other, wrap up, and place in the fridge for at least an hour (and up to three days) before using.
   

For the Flamingo Peas

1. First, cook your flamingo peas. Drain them from their soaking liquid and add to a big pot with all the other ingredients. Pour in enough water to generously cover, bring to the boil, and reduce to a simmer. Cook, keeping the liquid level above the peas, until tender — about 45 mins. This can be done well in advance, with the peas kept in their liquid in the fridge.

For the Filling

1. To make the filling, heat your oven to 180C. Chop the root veg into uneven chunks (careful of teeny parsnip ends which would burn), toss with oil and salt, and roast for half an hour to 40 mins, until sweet and soft and colouring at the edges.
2. Wash and slice your leeks. In a saucepan, heat the butter and add them in with a pinch of salt, the black pepper, and nutmeg. Cover and allow the leeks to fully cook down over a low heat for about 20 minutes. Meanwhile, measure out 600ml of the liquid from cooking your flamingo peas (topping up with water if necessary), and reheat.
3. Now add the flour to the leeks, stirring to combine into a sticky mess. Cook it out for about a minute, then add the white wine and beat well with a wooden spoon as it thickens. Add about a quarter of the warmed stock, again beating in well, until the sauce is glossy and bubbling. Gradually add the rest of the stock in this fashion, then simmer for a final few minutes.
4. Remove the pan from the heat. Stir in the mustard, double cream, and chopped sage leaves. Now stir through the roasted root veg and 400g of the flamingo peas, mixing thoroughly. Taste and adjust seasoning as necessary.
5. Cover and leave to cool completely. The filling is now ready — this makes enough for two pies, and freezes well.

Assembly 

1. Remove your pastry discs from the fridge and allow them to come up to temperature slightly while you thoroughly grease your 22cm dish. Preheat the oven to 180C fan.
2. On a lightly floured surface, roll out the larger pastry disc and carefully line your dish with it, leaving an overhang of excess pastry over the sides. Pop this in the fridge while you roll out the second, smaller disc of pastry.
3. Take out the prepped dish again and generously fill with the cold filling. Place the pastry lid on top, neatening and crimping together the edges to seal. Cut a slit in the middle of the pastry lid for steam, add any decorative detail you like from pastry scraps, and cover with egg wash.
4. Bake for 50 mins - 1 hour, or until golden. Leave to stand for 10 mins before serving.