Preheat the oven to 180ºC/350ºF/gas 4. Heat 2 tablespoons of rapeseed oil in a saucepan over a medium heat. Peel, slice and add the onion with a pinch of sea salt and cook for 5 minutes. Peel and chop the garlic, add with the cumin, bay and orange zest, and cook for 3 to 4 minutes.
Chop the chicken into 4cm chunks and add to the pan. Cook for 5 minutes, until sealed on all sides. Trim and add the carrots and flour, cook for a couple of minutes, then pour in the stock and crème fraîche. Stirring constantly, bring to the boil and let it simmer and thicken for a few minutes. Pick, chop and add the tarragon.
Pour the pie filling onto an ovenproof dinner plate (about 26cm in diameter). Beat the egg and use it to brush the edges of the plate. Roll out the pastry to the thickness of a £1 coin and top the pie, pressing down firmly around the edges to seal. Brush with beaten egg and place in the oven for 20 minutes, until the pastry is golden and the chicken is cooked through.
Meanwhile, trim and slice the runner beans into 1cm diagonal strips. Bring a small pan of salted water to the boil, add the peas and cooking for 2 to 3 minutes, then add the runner beans. Cook for a couple more minutes; drain, season and serve with your pie