For the mash, bring the stock to the boil in a saucepan. Add the potatoes and boil for 6-8 minutes, or until tender. Add the spring onions for the last two minutes of cooking time.
Drain off the stock, then return the potatoes and spring onions to the pan. Add the grated cheese and olive oil and mash together with a potato masher. Season, to taste, with salt and freshly ground black pepper.
For the orange butter sauce, place the orange juice and vinegar in a small saucepan over a medium heat and simmer for 3-4 minutes, until slightly reduced in volume.
Add the cream and simmer for a further 3-4 minutes, or until the sauce has thickened slightly.
Just before serving, add the cold butter to the hot sauce and whisk until smooth and glossy.
For the scallops, heat the oil in a small non-stick frying pan over a medium-high heat and fry the scallops for one minute on each side, or until just cooked through.
To serve, place the mash onto a serving plate, top with the scallops and pour over the sauce.