In a large skillet over medium heat, add the bacon and onion and stir.
Cook for 5 minutes, until bacon is almost cooked through. Using a slotted spoon, transfer bacon onto a paper towel lined plate.
Discard the bacon fat from the skillet. Transfer bacon mixture back into the skillet and add the tomatoes and basil.
Cook mixture for 5 more minutes, until bacon is very crisp and vegetables are tender.
In a large bowl, add the avocado, lettuce and cucumbers.
Spoon the bacon mixture over the top.
To a small bowl, add next 4 ingredients (olive oil through lemon juice).
Season with sea salt and freshly ground black pepper to taste.
Whisk together dressing.
Spoon the dressing over the bacon mixture and gently toss.