Add walnuts and sugar to a nonstick skillet over medium-high heat. Cook, stirring continuously, until sugar is melted and walnuts are evenly coated. Remove from heat and spread walnuts on wax paper or foil in an even layer; let cool completely.

In a mixing bowl, whisk together sauce ingredients until combined; set aside.

Heat olive oil in a large skillet over medium-high heat. Add cornstarch, salt, onion powder and garlic powder to a gallon-sized resealable bag; seal bag and shake to combine.

Add shrimp to the bag, seal and shake until shrimp is evenly coated. Cook shrimp in the preheated skillet for 2 minutes on each side. Remove shrimp from the skillet and repeat until all shrimp is cooked.

In a large mixing bowl, toss cooked shrimp and candied walnuts in sauce and garnish with sesame seeds and diced green onion before serving.