Preheat your water bath to 134°F (56°C).
Season the steaks on both sides to taste with salt, pepper and garlic powder.
Vacuum seal the steaks (or use the water displacement method) then cook for 8-10 hours.
Preheat another water bath to 147°F (63°C).
About an hour before the steaks are finished, combine all ingredients in a Mason jar or zip top freezer bag and place in the water to cook for 1 hour.
After searing steaks, remove from the water bath and empty ingredients into a blender (or use an immersion blender in the Mason jar). Process until emulsified.
This sauce breaks quickly - so make sure you do this just before serving. *You can also do this using the blender method - see note below.
While your cast iron pan is pre-heating, heat olive oil in another small pan over medium heat.
Add garlic and cook for 30-60 seconds.
Add the crab, lemon juice and Old Bay, and cook until just heated through.
Preheat your cast iron pan as hot as you can get it.
Remove the steaks from the bag and dry well.
Sear steaks on the first side for 30 - 45 seconds. If you want, you can use a torch to brown the sides while the bottom sears.
After 30 to 45 seconds, flip the steaks and sear for another 30 to 45 seconds or until nicely browned.
Place some steamed asparagus on a plate. Place one steak on top of the asparagus. Add half the crab mixture on top of the steak, then cover with a couple tablespoons of Béarnaise. Garnish with extra tarragon and a sprinkle of Old Bay.