Heat the oil and butter in a large saucepan. Add the crushed or ground coriander seeds and spring onions and stir-fry briskly for 1 minute.
Add the beetroot and the rice. Cook, stirring, for 2–3 minutes to coat all the grains with oil and butter. Gradually pour in the hot stock a ladleful at a time, stirring frequently until each ladleful is absorbed before adding the next. This should take about 25 minutes, by which time the rice should be tender, but retaining a little bite.
Stir in the cream cheese and dill and season to taste. Serve immediately, garnished with dill sprigs and a little crème fraîche, if using.