Bring a large pot of salted water to boil. Add the green beans and cook until crisp-tender, about 4 minutes. Drain and rinse under cold water. Drain again and refrigerate.
In a food processor, pulse the peanuts until coarsely chopped. Reserve 1/3 cup of the peanuts for garnish. Continue pulsing the remaining peanuts until finely chopped.
Add the vinegar, ginger, soy sauce, sugar, oil, 2 tablespoons of hot water and 1 teaspoon of salt to the peanuts and blend until the dressing is almost smooth, scraping down the sides of the bowl several times.
Toss the green beans with the dressing. Sprinkle the reserved chopped peanuts over the top just before serving.