Heat a sauté pan over medium heat and melt the butter. Add onions and sauté until beginning to turn translucent and tender, about 5 minutes. Add 2 Tbsp Hong Kong sauce and 1 tsp salt, stirring to combine. Continue cooking over low heat until the onions are lightly caramelized and very soft, about 15-20 minutes more. Remove from heat and allow to cool.\nOnce the onions are cooled, whisk together with remaining ingredients until well combined. Season to taste with salt. Top with sliced scallions and serve alongside chips, crackers or your favorite crunchy veggies!