Whisk the coconut milk with the red curry paste, brown sugar, lime juice and zest.
Pat the pork dry and season with salt and pepper. Place in a large resealable bag, or baking dish and cover with coconut milk mixture. Cover (or seal) and refrigerate 4 to 8 hours.
Preheat grill pan over medium high heat.
Remove pork from coconut milk and pat the pork dry and place in grill pan. Sear on all sides,about 6 minutes per side, until pork temps at 145 internally.
Let rest for 5 minutes before slicing and serving.
*I Served with roasted sweet potato and cauliflower. Whisked some additional coconut milk up with red curry paste and brought to a boil in a small saucepan. Served drizzled over top and sprinkled with cilantro.