Pat the fish fingers dry with a clean absorbent kitchen towel. Combine lemon juice, orange juice, salt, mustard paste, white pepper powder, dried thyme and Worcestershire sauce thoroughly. Mix the fish fingers in above marinade. Refrigerate the marinated fish fingers for about fifteen to twenty minutes.
Season whole wheat flour with salt and white pepper powder. Roll marinated fish fingers in seasoned whole wheat flour. Shake the excess flour off. Heat a non-stick tawa, slightly grease with a few drops of oil.
Place the fish fingers on it. Cook on medium heat, turning it occasionally for uniform cooking and colour. Cook till golden brown in colour.