I did this when i was in primary school.
1)Diced onions, skin peeled off.Fried lightly
2)Blend tuna in a blender
3)Microwave both 1) and 2) mixed.1-1.5 min on Medium- HI
4)Add mayo to tuna and stir properly.
I then usually dish the tuna onto lettuce that lies on crossaint
which i bought from carrefour.Try to copy delifrance. 