In a bowl mix together the spice mix, salt, lemon juice, and oil. Place pork tenderloins in a gallon resealable bag.
Pour marinate over the pork. Seal and coat evenly. Place in fridge and marinate for 8 hours.
Heat grill to medium. Remove pork from bag and discard marinade. Grill pork 4 minutes on each side (think of the tenderloin as having 4 sides). Test the pork with a digital thermometer to ensure it reaches desired temperature (I recommend 145°F).
Remove pork from grill, rent with foil, and allow it to rest 5 minutes before slicing. Serve immediately.