Mix together kosher salt, coarse ground pepper, garlic powder, and ground cinnamon. Rub the spice mixture over the 1 pound pork tenderloin. Place the tenderloin in a pan, cover, and refrigerate for 30 minutes.
Honey Sesame Sauce:
Put honey, soy sauce, olive oil, hoisin sauce, minced onion, minced garlic, sesame seed oil, and crushed red peppers in a sauce pan, whisk together, and bring to a boil over medium heat, stirring often.
In a small bowl, stir together cold water and cornstarch and then slowly whisk into the sauce. Continue cooking, stirring constantly, until thickened.
Put 1/4 cup of the sauce in a small bowl to bring out to the grill and set the rest aside.
Grilling:
Remove the pork tenderloin from the fridge and cut it into 1/2 thick slices. Brush the grill grates with vegetable oil and then cook the pork tenderloin medallions over high heat for 3 minutes on each side. Brush the pork tenderloin with the 1/4 cup of honey sesame sauce in the small bowl and grill an additional minute on each side to caramelize the sauce.
The pork is fully cooked once it has reached an internal temperature of 155˚F-160˚F.
Before serving, top the pork tenderloin with the remaining sauce and sprinkle with toasted sesame seeds and sliced green onions.
Notes
Bonus tip: If your honey sesame sauce gets too thick, you can thin it by whisking in water, a little at a time until it reaches the desired thickness.