Mix 1 tbsp salt and 500ml water in a bowl. Add frozen seafood mix and let it thaw for 30 minutes.

Boil water in a pot, drain the thawed seafood mix, and boil for 1 minute. Drain and let cool.

Tear green leaf lettuce into bite-sized pieces. Halve cherry tomatoes. Thinly slice onion, sprinkle with a pinch of salt, massage briefly, let sit for 5 minutes, then squeeze out excess water.

In a large bowl, mix the dressing ingredients. Add the cooled seafood mix and prepared onion, then toss well.