1)  Slice each porrk tenderloin in half CROSSIWSE to create 4 steaks total.  Pound each half to 3/4" thickness.  Using a sharp knife, cut 1/8" deep slits spaced 1/2" apart in crosshatch pattern on both sides of steaks.  

2)  Whisk lime zest and juice, garlic, honey, fish sauce, salt & pepper  together in a large bowl.  Whisking constantly, slowly drizzle oil into lime mixture until smooth and slightly thickened.  Transfer 1/2 cup lime mixture to small bowl and whisk in mayonnaise, set aside sauce.  Add steaks to bowl with remaining marinade and toss thoroughly to coat; transfer steaks and marinade to large zipper-lock bag, press out as much air as possible and seal bag.  Let steaks sit at room temperature for 45 minutes.

3)  FOR A GAS GRILL:  Turn all burners to high, cover and heat grill until hot, about 15 minutes.  Leave primary burner on high and turn off other burner(s) 

4)  Clean and oil cooking grate.  remove steaks from marinade (do not pat dry) and place over hotter part of grill.  Cook, uncovered, until well browned on first side, 3-4 minutes.  Flip steaks and cook until well browned on second side 3-4 minutes.  Transfer steaks to cooler part of grill, with wider end of each steak facing hotter part of grill.  Cover and cook until meat registers 140 degrees, 3-8 minutes.  Transfer steaks to carving board and let rest for 5 minutes. 

5)  While steaks rest, microwave reserved sauce until warm  15-30 seconds, stir in cilantro.  Slice steaks against the grain into 1/2 in thick steak slices.  Drizzle with half of sauce; sprinkle with sea salt and serve, passing remaining sauce separately.