Heat a sauté pan over medium heat and melt butter. Add onions and sweat until beginning to turn translucent and tender, about 5 minutes. Add 2 Tbsp Hong Kong sauce and 1 tsp salt and stir to combine. Continue cooking until onions are lightly caramelized, about 10-15 minutes more. Remove onions from heat and allow to cool.\nOnce onions are cooled, whisk together with remaining ingredients until well combined. Season to taste with salt. Top with scallions and serve with chips or your favorite crunchy veggies!