Toss the rabbit joints (or diced meat) with half the flour and some seasoning. Heat half the oil in a flameproof casserole dish and brown the meat on all sides. Lift out the meat, add the remaining oil, the leek and fennel seeds, and fry gently until softened. Stir in the remaining flour until it has disappeared. Add the cider and scrape up any stuck bits on the dish as it comes to the boil, then add the stock, return the meat to the dish, and bring to a simmer.
Cover and cook for 40-45 mins until the rabbit is really tender and falling from the bone. Lift out the meat and, while you’re shredding it from the bones in big chunks (if you’ve used joints), boil down the cooking liquid to about a third.
Stir the cream and mustard into the liquid, taste for seasoning, then stir the rabbit back in. Spoon into a small pie dish or baking dish.
Heat oven to 200C/180C fan/gas 6. Stick a thin strip of pastry around the edge of the dish. Slice the remaining pastry into 2.5cm-wide strips with a floured knife, then weave into a tight lattice. Lift up carefully, using a rolling pin to help you, then stick on with a little beaten egg. Trim the edges to finish. Brush the top with more egg and bake for 25 mins until golden.
Meanwhile, bring a saucepan of salted water to the boil. Add the carrots for 2 mins, then the radishes for 2 mins, followed by the peas for 1 min. Drain. When the pie is done, melt the butter in a small frying pan. Add the drained veg with the sugar, turn up the heat and fry to caramelise a little. Serve immediately alongside the pie.