Lobster, baked purple potatoes and Gruyère sauce

To bake the potatoes, first preheat the oven to 200°C/gas mark 6

Wash the potatoes in cold water and then pat dry. Rub the skins with a little oil and sprinle with sea salt

Bake the potatoes for 1-1½ hours or until tender

Remove the potatoes from the oven and set aside to cool slightly. Don’t turn off the oven. When the potatoes are cool enough to handle, cut them in half and scoop out the flesh, retaining the skin. Pass the flesh through a fine sieve into a saucepan. Add the butter to the potato and mix through to incorporate thoroughly. Set aside and keep warm

To make the sauce, heat the cream, mustard, lemon zest and juice together in a pan until it comes to the boil

Take the sauce off the heat and whisk in the egg yolks until combined. Stir in the Gruyère and add the basil. Season to taste with sugar, salt and freshly ground black pepper and continue to cook until the sauce thickens. Take off the heat

Increase the oven temperature to 220°C/gas mark 7

Divide the buttery potato mixture between the potato skins and add the lobster and a spoonful of Gruyère sauce over the top

Bake the potatoes in the oven for 3 to 4 minutes or until the sauce is bubbling and serve immediately