Mix shrimps, beansprouts, lemongrass, and galangal in a bowl.
Whisk tamarind paste, soy sauce, and sake together, then stir into the shrimp mixture.
Stir in chilli, coriander, and white pepper, adding palm sugar if the mixture is too sharp.
Brush a wrapper with beaten egg, fill with shrimp mixture, and roll tightly like a cigar.
Heat oil in a heavy pan until a breadcrumb sizzles and browns.
Fry rolls in batches until golden brown and hot inside.
Grind garlic, ginger, chillies, and sugar to a paste, then mix with lime juice and fish sauce.
Combine all vinaigrette ingredients in a bowl and mix well.
Serve spring rolls on a bed of watercress with both dipping sauces.