Place prepped tuna into a large salad bowl.
Add in diced avocado, cucumber slices, sliced onions, and parsley or cilantro. Set aside.
In a small mixing bowl combine olive oil, lemon juice, salt, and pepper; whisk to combine.
Taste for seasonings and adjust accordingly. I almost always add more lemon and salt.
Add salad dressing to the salad; toss to combine.
