Combine the sliced red onion, lime juice, and salt in a small bowl and mix. Cover and set aside at room temperature for 30 minutes.
Preheat Blackstone griddle to medium heat. Lay out the bacon and cook for 10-15 minutes or until desired doneness. Set aside on a paper towel-lined plate.
Grease 4 Blackstone egg rings and set them onto the griddle. Divide the beaten eggs between them. Cook for 4 minutes until solid then remove the rings. Flip the eggs and top with 2 slices of cheese. Cover for 1 minute to allow the cheese to melt.
While the cheese is melting, lay out the croissants onto the griddle and let toast. Remove from the griddle and spread pesto on to each side.
Build the sandwich by layering the eggs, bacon, spring mix, and pickled onions. Serve immediately.
