Preheat oven to 350 degrees F. Toast the bread slices and let cool.
Roast the bacon in oven until crisp.
Chop red onion, tomato, cilantro, garlic, mint leaves, and jalapeno finely. Put in a bowl. Add the avocado and pour in lime juice. Toss the avocado mixture and season well with salt and pepper.
Place 1 tablespoon avocado mixture on each slice of gravlax. Fold the gravlax into a square, so that the avocado is wrapped in the center. Place the bacon and gravlax between 2 slices of bread. Cut the sandwich diagonally. Place a rosette on top each half and place 2 pieces of bacon on top of the rosette.