VINAIGRETTE – In the small jar, shake the fish sauce, lime juice, olive oil, palm sugar, sea salt, garlic, lemongrass, and hot chili sauce. Allow to set for at least 30 minutes.
SALAD – Cover the beans in water in the large pot, and bring to a boil. Reduce heat to medium and cook beans until crisp tender, about 8 to 10 minutes. Drain and immediately transfer to an ice bath in a medium bowl. Allow beans to cool, then drain. Add the sliced mango, bell pepper, red onion, and cilantro leaves. Toss with the vinaigrette and chill for at least 2 hours before serving.