Make garlic aioli by mixing mayonnaise, minced garlic, lemon juice, a sprinkle of salt, and a dash of cayenne in a small bowl. Cover and refrigerate for 30 minutes.
Cover a baking sheet with foil. Using 8 bacon slices for each, form bacon into 2 weave patterns on the foil by using “under-over” layering. Place into a cold oven and set temperature to 350° F. Cook for 15-20 minutes, or until desired doneness. Drain bacon weaves on a paper-towel lined plate.
Carefully and evenly slice focaccia in half (to form a top and bottom). Optional to wrap in foil and warm in the oven for the last 5 minutes of cook time of the bacon cooking if desired. You can also make these sandwiches on un-toasted bread.
When ready to assemble sandwich, spread garlic aioli on bottom, and pesto on top. Layer bacon, tomatoes, and red onion slices. Place the top of bread on top. Cut into triangles and serve!