For the marinade, mix mirin, sake, miso, soy sauce, sesame oil, garlic powder, ginger and red pepper in small bowl until well blended. Reserve 1/2 cup of the marinade for the glaze. Place pork in large resealable bag. Add remaining marinade; turn to coat well. Refrigerate 30 minutes.
Meanwhile, for the glaze, mix reserved marinade, brown sugar, cornstarch and water with whisk in small saucepan until well blended. Bring to boil on medium heat. Reduce heat to low; simmer 2 to 3 minutes or until slightly thickened. Remove from heat.
Remove pork from marinade. Discard any remaining marinade. Alternately thread pork and pear onto bamboo skewers.
Soak bamboo skewers in water for at least 30 minutes to prevent burning.
Grill skewers over medium heat 2 to 3 minutes per side or until pork is to desired doneness, brushing evenly with glaze while cooking. Brush grilled skewers with any remaining glaze just before serving. Sprinkle with green onions, if desired.