In a large pan over medium high heat, cook your bacon strips until you reach the desired level of crispness. You could also place them in a cooling rack over a baking sheet in an oven at 375° for 15-18 minutes
Meanwhile, in a separate pan over medium hear, melt butter and crack 4 eggs into the pan. Cook low and slow until the egg white set but the yolks are still a bit runny.
While the bacon and eggs cook, toast your bread to your liking
On the slice of toast, spread a heaping tbsp of mayo (I used a homemade herb mayo), and a few tsps of the sun dried tomato pesto on the other.
On one toast with the mayo, layer on some leaves of romaine, a few thick slices of tomato (seasoned with salt). Top that with 2-3 slices of bacon and one of the sunny side up eggs.
Top the sandwich with the other piece of toast, slice in half. Repeat 3 times and serve immediately.