Start by prepping the salmon. Mix mirin, miso, ginger and garlic in a large ziplock bag or deep dish. Place salmon into the marinade and slosh around to get it coated. Let it sit in the fridge for an hour up to overnight. The longer the better.
About 30 minutes before you want to cook the salmon, pull the salmon out of refrigerator to get it to room temperature.
Preheat the oven to 350 degrees Fahrenheit. Place the bacon on a sheet pan covered with parchment paper and bake in the oven 20 minutes or until crisp. When the bacon is done, turn the oven to broil. If you don’t have a broil setting, turn the oven to its highest temperature.
Place salmon 6 inches under the broiler and bake for 10-12 minutes. It will get a char on top but trust me, it is delicious. When it is done cooking, remove from the oven and let it sit 5 minutes. Then remove the skin from under the salmon by sliding a spatula underneath. I use my fish spatula because it is flexible enough to get under the skin.
Toast the ciabatta until crisp. Mash the avocado until its a guacamole consistency and spread over one piece of the bread. Place two slices of bacon on each sandwich and then a sliver of the salmon.
Notes
Kid-Friendly Adaptation: Got a picky eater? I know salmon isn't the most kid friendly food. This tastes just as good when using chicken breast instead! Just slice in half length wise so it cooks completely in the oven!