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.
Serve warm.