Meanwhile, for the avocado salsa, mix the diced avocado, onion and cucumber together in a bowl until well combined. Season, to taste, with salt and freshly ground black pepper and a squeeze of ...

Dip a piece of the fish into the mixture and taste for seasonings, adjusting as needed. Pour the sauce over the tuna and mix gently. Halve the avocado and remove the pit. Cut the flesh into cubes ...