Preheat the oven to 200°C, 180°C fan, Gas Mark 6.
Simmer the honey, juices, rinds, vanilla bean and seeds in a small saucepan over a medium heat until reduced to a light syrup (8-10 minutes). Place the pears, cut-side up in a roasting pan large enough to fit the pears snugly. Pour over the honey mixture and roast, basting occasionally, until tender and beginning to caramelise (20-25 minutes).
Remove the pears from pan and serve the pears and syrup with yogurt and pistachios.