Cook all bacon slices over medium heat in a large sauté pan until very crispy (about 8 minutes). Remove from pan and place onto a plate that has two sheets of paper towel lined on top of it. Allow the grease to drain and the bacon to cool slightly.
Toast all slices of bread, then spread an equal amount of mayonnaise onto the top side of each slice.
Sprinkle the chopped red onion and freshly grated sharp cheddar cheese directly onto the mayonnaise spread. This allows the mayonnaise to bind with the looser ingredients and keep the in place.
Cut each romaine leave into slices that fit onto the bread slices, and gently lay them over the mayonnaise, red onion and cheddar on the bottom half of each sandwich.
On top of the romaine, place your thick slice of garden fresh tomato. Crack black pepper and sea salt directly onto both tomato slices.
Tear the bacon into pieces that are about three inches long, and lay across the top each tomato, covering each tomato entirely with bacon slices. Gently transfer the top half of each sandwich, mayonnaise side down, onto the bacon, and squish down gently before cutting each sandwich diagonally to form a set of triangles.
Don't skip on the salt and pepper on the tomato. It's key.