Wash and brush the potatoes and wrap them in foil. Cook in the preheated oven (electric cooker: 200 °C/ gas: level 3) for about 45 minutes. In the meantime, mix sour cream, salt, pepper and lemon juice. Remove potatoes from the foil. Cut the potatoes crosswise and arrange them. Spread the sour cream and caviar on top, garnish with chives