Thinly slice the red onion and soak it in ice water for 30 minutes to soften the bite and keep it crisp. Drain well.

Heat 1 tablespoon of the olive oil in a wide pan over high heat. Sear the squid rings for 3 minutes. Add the shrimp and cook 3 minutes more, just until done. Transfer the seafood to a large bowl.

In the same pan, cook the mussels covered until they open. Remove the meat and discard the shells. Strain the cooking liquid through a paper filter and keep it warm.

Add the bread cubes to the bowl with the seafood, halved tomatoes, cucumber, and drained onion.

Pour the warm strained mussel liquid over the bread so the crumb drinks in the brine.

Dress with the remaining olive oil, lemon juice, lemon zest, salt, and pepper. Toss gently, then fold in torn basil and lemon thyme.

Rest for 15 minutes before serving, so the bread turns tender but keeps its chew.