Toss shrimp, salt, pepper, and sugar together in medium bowl. Heat 1 tablespoon vegetable oil in 12-inch nonstick skillet over high heat until just smoking. Add shrimp in single layer and cook without stirring until beginning to brown, about 1 minute. Stir shrimp and continue to cook until light pink and all but very centers are opaque, about 30 seconds.
Transfer shrimp to bowl, cover to keep warm, and set aside.
Add remaining 1 tablespoon vegetable oil to now-empty skillet and heat over medium-high heat until shimmering. Add bell pepper and peanuts and cook until pepper is softened, about 2 minutes. Transfer to bowl with shrimp.
2 tablespoons vegetable oil, 1 red bell pepper, ½ cup dry-roasted peanuts
Add garlic, ginger, and pepper flakes to oil left in skillet and cook over medium-high heat until fragrant, about 30 seconds. Stir in broth. Break bricks of ramen into small chunks and add to skillet. Bring to simmer and cook, tossing ramen constantly with tongs to separate, until ramen is just tender but there is still liquid in pan, about 2 minutes.
Stir in hoisin, vinegar, and sesame oil and continue to simmer until sauce is thickened, about 1 minute. Return shrimp-pepper mixture to skillet and cook until warmed through, about 1 minute. Sprinkle with scallions and serve.