Pour the tuna into a sieve and drain well. Pluck the tuna apart. Put mayonnaise, sour cream, capers with liquid and tuna, except for 2 tablespoons, into a high mixing bowl and puree with a blender.
Season to taste with salt, pepper and lemon juice. Prepare pasta in boiling salted water according to package instructions. Meanwhile, clean and wash the rocket and drain in a sieve. Wash the mint, shake dry and pluck the leaves from the stalks.
Drain the pasta and let it drain. Mix the pasta, half rocket, half mint leaves and tuna sauce. Arrange on plates. Sprinkle with olives, rest of rocket and mint and tuna. Garnish with caper apples.