In a medium bowl, combine soy sauce, brown sugar, toasted sesame oil, minced garlic, and grated ginger. Stir until the sugar is dissolved and the mixture is well combined.

Add the shrimp to the marinade and toss to coat. Allow the shrimp to marinate for at least 15 minutes or up to 1 hour in the refrigerator for better flavor.

In a small bowl, mix cornstarch and water until smooth. Set aside.

Heat a large skillet or wok over medium-high heat. Once hot, add the marinated shrimp along with the marinade. Cook for 3-4 minutes, stirring occasionally, until the shrimp turn pink and are cooked through.

Pour the cornstarch mixture into the skillet and stir well to combine. Cook for an additional 1-2 minutes until the sauce thickens slightly.

Remove from heat and garnish with sliced green onions and sesame seeds.

Serve immediately over steamed rice or noodles, if desired.