Fry or grill catfish fillets until fully cooked.
Roast garlic, shallots, and jalapeño until they are softened and slightly charred. Let them cool and then paste them with a mortar and pestle or food processor.
Cook prahok with 1/2 cup water. Alternatively, prahok can be baked in the oven.
In the mortar, combine the catfish, roasted garlic, shallots, jalapeño, and prahok, and smash the ingredients together until semi blended.
Transfer the paste to a larger bowl and add the juice of one lemon, sugar, and msg. Mix well to combine.
Adjust the seasoning according to your taste preferences. Fish sauce can be used to bring up savory.
Allow the flavors to meld by refrigerating the dip for at least 30 minutes.
Serve the catfish prahok dip with fresh or cooked vegetable and some steamed rice.