Use a wide but shallow wooden spoon. Put each beetroot into the bowl of the spoon, use a sharp knife cut slices NEARLY all the way through, a few mm apart.
Place on a small parchment-lined baking tray and fan the slices out. Spoon the melted butter evenly over, especially between the slices.
Roast for one and a quarter hours at 190° , basting very well every 20 minutes or so, until the edges are crisp and caramelised. Set aside to cool for 15 minutes.
Spread the yoghurt cream on a platter, then arrange the beets on top, spooning the butter over. Drizzle over the salsa, finish with remaining lime juice and serve at once.