(Optional) Hard-boiled eggs: Preheat the air fryer to 250°F. Add the eggs and cook for 15 minutes. Transfer to an ice bath for 10 minutes, then peel and thinly slice.
Season the bacon (optional): In a small bowl, combine the brown sugar, black pepper, and paprika. Rub onto both sides of the bacon.
Cook the bacon: Preheat the air fryer to 370°F. Add ¼ cup water to the drawer under the basket to reduce smoking. Arrange the bacon in a single layer and cook for about 10 minutes, until crisp. Drain on a paper towel-lined plate.
Make the aioli (optional): In a blender or food processor, blend the mayonnaise, garlic, Dijon mustard, and lemon pepper until smooth.
Toast the bread: Spread mayo or aioli on the bread slices. Place in the air fryer at 370°F and toast for about 1 minute, until golden.
Assemble: Spread the toasted bread with mayo or aioli. Layer on the lettuce first (it keeps the bread from getting soggy), then tomato — seasoned with a pinch of salt and pepper — then crispy bacon. Add egg and avocado slices if using. Top with the second slice of bread.
Serve immediately and enjoy.