Preheat a large skillet over medium-high heat with 1 turn of the pan EVOO, about 1 tablespoon. Add the bacon and cook until crisp on both sides. Remove from the skillet to a paper towel-lined plate to drain. Break the bacon slices in half and reserve. Let the skillet cool a bit and wipe it out with a paper towel for the tuna.
Place the avocados in a bowl along with the lime juice and some salt and pepper, smash until some what smooth with a fork, reserve.
Toast the bread slices under the broiler but keep an eye on it so it doesn't burn!
Preheat the skillet over medium-high heat. Sprinkle the thin tuna steaks with the chipotle powder, drizzle a little EVOO over them and transfer to the skillet.
Cook on each side for 2-3 minutes or until it reaches desired doneness.
To assemble the sandwich, spread the avocado mash on a slice of bread. Top with a slice of tuna, 2 half-pieces of crispy bacon in an X, some lettuce, a slice of tomato, another piece of tuna, 2 more half-pieces of bacon, more lettuce and another slice of tomato.
Slather the last piece of bread with a little more of the avocado mixture and place it on top of the sandwich. Place a toothpick in each of the 4 corners of the sandwich then cut the bread into 4 triangles -- the toothpicks will help hold it together. Serve with chips alongside.