Mix 1 1/2 teaspoons of the cinnamon, lemon peel, 1/2 teaspoon of the sea salt, pepper and cayenne pepper in small bowl. Brush pork lightly with 1 tablespoon of the oil. Coat evenly with spice mixture.
Grill pork over medium heat 15 to 20 minutes or until desired doneness, turning occasionally. Grill plum wedges 1 to 2 minutes on each side or until slightly tender. Transfer pork on cutting board. Let stand 5 minutes before slicing.
Mix lemon juice, remaining 3 tablespoons oil, honey, and remaining 1/2 teaspoon each cinnamon and sea salt in small bowl with wire whisk until well blended.
Slice pork on an angle into thin slices. Divide salad greens among 4 serving plates. Top each with pork slices, plums and onions. Serve immediately with dressing.