Clean the same wok or pan, return it to medium-high heat, and add 1 tablespoon of fresh oil.
Once the oil is hot, add the ginger, garlic, and white parts of the scallion and cook for 1-2 minutes, stirring constantly, until lightly browned.
Lower the heat to medium and add the ketchup and doubanjiang. Cook for 1-2 minutes, stirring constantly, until the ketchup and doubanjiang become fragrant.
Add the chicken broth, sake, and sugar, and simmer for 2-3 minutes, stirring frequently.
Add the partially-cooked shrimp and the green parts of the scallions, and simmer until the shrimp are cooked through, about 1-2 minutes.
The cornstarch slurry may have separated, so use a spoon to stir it again. Then add the cornstarch slurry to the pan and stir. Cook for 1-2 minutes until the sauce is thickened, stirring constantly.
Add the sesame oil and stir. Remove the pan from the heat.