Cut the tips off the cucumber. Using a vegetable peeler or mandolin, shave the cucumber lengthwise into thin strips.

Place the slices in a colander and sprinkle with about a teaspoon of sea salt. Leave them to drain for 15 minutes. Rinse in cold water and pat dry with kitchen towel.

In the meantime, drain the tuna in a separate colander for 15 minutes. Transfer to a mixing bowl.

Loosen up the big chunks of tuna with a fork and mix in the yogurt, paprika, garlic, salt and pepper. Mixture should be a bit moist.

Place cucumber slices on a cutting board and divide the tuna mixture evenly according to the number of cucumber slices. Place a teaspoon or so of the tuna mixture on the botton of each slice, about an inch from the edge. Place two pieces of avocado on the end on the slice that has the mixture on it and roll tightly starting on that end.

Whisk the yogurt, olive oil, curry powder, salt and pepper together and serve the cucumber-tuna rolls.