Coarsely crush the peppercorns preferably with a pestle and mortar. Rinse the tuna steaks in cold water, remove any excess moisture with a piece of kitchen towel then coat both sides evenly with the crushed peppercorns.
Heat the olive oil and butter in a heavy based frying pan over a fairly high heat. Just as the butter is starting to turn a light brown colour reduce the heat and place the peppered steaks in the pan. Cook for about 2 minutes each side.
Carefully pour in the brandy and flambé. When the flames have subsided remove the tuna steaks carefully from the pan and place into a serving dish, keep warm.
Add the double cream to the pan and stir quickly until gently bubbling. Pour the sauce over the tuna steaks and serve immediately. Delicious!