Crush your roasted peanuts in a mortar and pestle, or alternatively give them a coarse chop with a chef's knife. Set aside.
Finely chop the garlic and Thai chili pepper. Add to a bowl, along with fish sauce, lime juice, and palm sugar. Stir until the palm sugar is dissolved.1
Before you're ready to serve, add the crushed peanuts to the sauce.
To Make the Fried Fish:
Wash and dry your fish filet. Cut into bite-sized cubes.
Coat the fish with the Gogi tempura flour, using as much as needed to achieve an even, consistent white coating.2
Heat the oil over medium high heat. Once the oil is hot, add your coated fish pieces and allow to cook for 2-3 minutes, until they are golden brown on the outside and cooked through on the inside. Allow to drain in a colander or on a paper towel. Sprinkle with salt while still hot.
To Make the Appetizer:
Peel the shallot and ginger and slice both into small cubes.
Roast the peanuts by dry frying in a pan over low to medium heat, according to this article.
Cut the Thai chili peppers into small slivers. Slice the lime into small segments, keeping the peel on as long as it is thin enough. If the peel of the lime is too thick to easily eat, it should be removed.
Assemble all of the ingredients on a plate, surrounding a bowl of sauce in the middle. Encourage each diner to make their own parcel with a leaf, a piece of fried fish, the fresh ingredients they'd like, and a drizzle of the sauce. Enjoy while the fried fish is still hot!
Notes
If you are starting with a hard block of palm sugar, you can help it to dissolve by slicing it into very fine shreds before mixing it with the liquid ingredients. Alternatively, you can add several drops of water to the hard sugar and microwave it for several seconds until the sugar melts, then combine it with the liquid ingredients.
If you do not have Gogi flour, you can substitute cornstarch.