Heat oil in large skillet and toss in spices and garlic and saute until garlic is dark golden. Remove star anise and garlic.
Salt and pepper fish fillets. Sear skin side down first then turn and finish cooking.
Toss together corn kernels watercress and scallions. Whisk together all dressing ingredients except oil. Then slowly drizzle in oil while continuing to whisk. Pour in enough oil so dressing becomes thick and creamy and not too acidic. Season, to taste, with salt, pepper and sugar.
For the dressing: Whisk together the lemon juice, mayonnaise, Dijon, salt, pepper and sugar to taste. Whisk in the vegetable oil until emulsified. Toss the corn, watercress and scallions together and add enough of the dressing to coat the salad.