In a medium sized skillet add the olive oil over medium high heat. Add the bell pepper and garlic and sauté until almost tender. Add the shrimp and cook for 2-3 minutes until pink.
In a small bowl whisk soy sauce, sesame oil, brown sugar, sriracha, and red pepper flakes. Mix together the cornstarch and water and whisk into the sauce. Pour sauce over the shrimp mixture and add peanuts.
Sauté until it starts to thicken and coat the shrimp. Garnish with sliced green onions if desired.