Add maple syrup, white balsamic, mustard, rosemary, salt, pepper, and sliced chilies to a bowl and stir to combine. Place pork tenderloins in a small baking dish or resealable bag and pour over marinade.
Cover/seal and refrigerate for 4 to 24 hours. Turning pork occasionally.
Preheat grill on medium heat to approximately 400˚F - 425˚F.
Remove pork from marinade allowing excess marinade to drip back into the dish.
Add the marinade into a small saucepan and bring to boil over medium-high heat. Boil for 4 minutes stirring occasionally. Then remove from the heat until ready to serve. Note: It is important to boil the marinade to completely kill off bacteria from the raw pork. If you are concerned about this process, just double the marinade quantities, reserve half, and discard the marinade that the pork was submerged in. Warm reserved marinade before basting and serving.
Place the pork over direct heat and grill for 4 to 6 minutes until nicely charred. The sugars in the maple syrup will burn, so watch this step carefully and adjust the heat as required. Flip the pork and brush with a little of the boiled marinade. Grill for 4 to 5 minutes more, until nicely charred. At this point, either move the tenderloins to an upper rack or an area of the grill that they can continue cooking over indirect heat with the lid closed. Cook until the internal temperature reaches 145˚F (12 to 20 minutes, depending on thickness of the pork, how often the lid is open and outside temperature).
Remove pork and tent loosely with foil. Let rest for 10 minutes before slicing pork into ½ inch thick slices on a diagonal. Serve drizzled with spoonful of warm sauce.
We enjoy this dish with a variety of grilled vegetables, and crispy smashed potatoes.