Preheat the oven to 150°C. Carefully wash the beetroot, taking care not to pierce or bruise the skins. Wrap each one in a square of buttered foil and put in a roasting pan. Bake in the oven for 3 – 3 1/2 hours, or until the skins come away easily when rubbed gently.
Remove from the oven and, when cool enough to handle, peel carefully and cut into quarters. Melt the butter in a large frying pan, add the beetroot, spring onions and herbs and toss gently until coated with the butter. Remove the beetroot and put into a heated serving dish. Add the cream to the pan, bring to the boil, boil for a minute, then pour over the beetroot.
Sprinkle the beetroot with the gherkin strips and serve with roast pork, grilled loin chops or crispy roast duckling.