Boil eggs in water for 9 minutes until hard. In the meantime drain the tuna. Peel onion and chop coarsely. Puree tuna, diced onion, capers and salad cream. Cut 3/4 of the cress from the bed and stir into the tuna cream.
Clean and wash the radishes and cut 8 of them into fine slices. Cut feta into thin slices. Rinse eggs with cold water, peel and slice. Toast the slices of toast. Spread 4 slices of toast thinly with tuna cream. Cover with slices of feta, radishes and eggs. Spread wholemeal bread slices generously with tuna fish cream. Place the wholemeal bread slices on the toast slices and finish with the remaining toast slices. Cut the remaining cress from the bed.
Cover with slices of feta, radishes and eggs. Spread wholemeal bread slices generously with tuna fish cream. Place the wholemeal bread slices on the toast slices and finish with the remaining toast slices. Cut the remaining cress from the bed. Cut sandwiches diagonally in half and sprinkle with cress. Serve the rest of the tuna cream and radishes with it