Finely chop red onion and parsley. Peel the cucumber randomly, remove seeds, cut into 4 even pieces, and cut again coarsely. Squeeze the lime and lemon.
Peel and devein the shrimp if needed, and wash well. Boil water in a pot, add salt, put in the scallops and shrimp, and cook quickly. Remove from heat and plunge in ice water. Drain when completely cool.
The water used for boiling should be a bit salty to season the shrimp and scallops. Drain well on paper towels.
Cut the shrimp and scallops into bite-sized pieces and toss in a bowl. Add ingredients from Step 1, saving half of the lemon juice for later use. Add a pinch of salt, cover with plastic wrap and chill in the refrigerator.
It's best to chill for at least 2 hours to allow the flavors to be absorbed It can be made the day before.
Add avocado just before serving. Sprinkle the remaining lemon juice on the avocado and mix together lightly. Transfer to serving plates, and it's ready.
Story Behind this Recipe
I was looking for a simple and lightly flavored appetizer and came up with this. I got the idea from dips I've made in the past.
You can use any kind of seafood you like. Avocado discolors easily, so sprinkle lemon juice it right away after cutting. I add parsley beforehand, but if you add with the avocado, it'll brings out the fresh aroma.