Skin the whitefish fillets and cut into 2-inch pieces.

Marinate the fish in a mixture of egg white, cornstarch, white wine, salt, and pepper.

Heat oil in a wok on medium-high heat.

Fry the fish in batches until golden brown and crisp. Drain on paper towels.

Remove excess oil from the wok, leaving about 1 tablespoon.

Stir-fry onion wedges for 1-2 minutes.

Add curry powder and cook for another 1-2 minutes.

Add pineapple and mandarin orange juice and bring to a boil.

Combine a spoonful of the boiling juice with cornstarch and lime juice mixture.

Return this mixture to the wok and cook until thickened, about 2 minutes.

Taste and add sugar if desired.

Add the fruit, water chestnuts, and fried fish to the wok and stir to coat.

Heat through for 1 minute and serve immediately with rice or noodles.