Pat dry shrimp. Season both sides with garlic powder, salt, and ground black pepper. Set aside.
Blanch broccoli florets in boiling water for 1 to 3 minutes. Transfer broccoli florets to a bowl of ice water for 3 to 5 minutes. Using a slotted spoon, transfer broccoli to a plate. Set aside.
In a small bowl, combine the ginger garlic sauce - ginger powder, garlic powder, chili garlic sauce, light brown sugar, soy sauce, rice vinegar, and water. Stir well. Set aside.
In a heated skillet (or wok) with oil, pan-fry shrimp for 1 to 2 minutes on each side. Remove shrimp once they start to curl up or when the color is no longer translucent. Do not overcook. Transfer to a plate. Set aside.
In the same skillet, stir-fry garlic and ginger for 1 to 2 minutes, until fragrant.
Add red onions and red bell peppers then continue to stir-fry until crisp-tender.
Pour half of the ginger-garlic mixture, salt, and ground black pepper. Continue to stir-fry for 2 to 3 minutes.
Meanwhile, combine cornstarch and water to make a cornstarch slurry. Mix well.
Toss in shrimp and broccoli. Pour the remaining ginger-garlic mixture. Give it a quick toss.
To thicken the sauce, stir in the cornstarch slurry, adding 1 tablespoon at a time. Stir quickly until the sauce thickens.
Transfer to a plate. Garnish with fresh spring onions (green onions). Serve immediately.