Boil eggs in boiling water for about 10 minutes until hard. Cut a lid off the pointed peppers, remove the seeds. Wash the bell peppers and dab dry. Peel onion and cut into fine cubes.
Cut the gherkins into fine cubes. Drain the capers. Drain eggs, quench, peel and cut into small cubes. Drain tuna and chop. Mix onion, gherkins, capers, eggs, tuna and crème fraîche, season with salt, pepper and sugar.
Fill into the peppers and put the lids back on. Arrange in a bowl.