Drain the olive oil from the tuna can and gently flake the tuna in a strainer.
Chop the red onion and cilantro finely; green onion can substitute for red onion if preferred.
Slice the avocado in half and carefully remove most of the flesh, leaving a thin layer inside the skin.
Place the scooped avocado in a bowl and mash it well with a fork.
Blend in olive oil, mayonnaise, lime juice, salt, and pepper into the mashed avocado.
Fold the flaked tuna into the avocado mixture.
Add the chopped cilantro and red onion and combine gently.
Adjust the seasoning with salt and freshly cracked black pepper.
Spoon the mixture back into the avocado halves.
Serve with lime wedges for extra zest if liked.
