Bò nhúng giấm in Vietnamese literally means “beef dipped in vinegar”. The dish is prepared with a vinegar-based hot pot, then raw beef slices will get dipped first in the hot pot to get cooked and then in a dipping sauce. However, this is not a real hotpot dish because diners will not dip vegetables in the hot pot. Dipped beef slices can be eaten as is, or can be wrapped and rolled with bún noodle (Vietnamese rice vermicelli) like spring rolls.
The dipping sauce is made from “mắm nêm” sauce , a pungent fermented fish sauce, mixed with several ingredients to balance the taste.
In a saucepan, heat the oil and sauté minced garlic, lemongrass, and chilli. Next, add 2 tablespoons of "mắm nêm" sauce, 1 tablespoon of sugar, a bit MSG, and ½ bowl of pineapple juice, and stir the mixture evenly. When the mixture gets to a boil, turn off the heat and let the sauce cool. Right before serving, put in some pineapple pulps and season the sauce to suit your taste buds.
Heat oil in a pot, and sauté minced ginger, chopped Asian shallots, and crushed lemongrass. Next, pour 800 ml (~ 3 cups) of hot water into the pot along with rock sugar, salt, granulated sugar, vinegar and some MSG. Stir the vinegar broth. When the broth comes to a boil, add onion wedges and turn off the heat.
If you can't eat the "mắm nêm" sauce, this might not be a dish for you. You may change the dipping sauce to more friendly one you like.
Alternately, you can prepare the vinegar broth in a stone bowl.