Clean the basa fish well and cut to make fingers. Set aside. In a bowl, add ginger garlic paste, mustard sauce, finely chopped parsley and lemon juice and mix well. Add egg white and mix while you keep adding the refined flour slowly. Thus make a batter and add salt and crushed black pepper. Take the fish fingers and coat them first with the prepared batter and then with the bread crumbs. Heat oil for frying and deep fry the fish fingers till they turn a golden brown. Set aside on a tissue paper. Serve the fish fingers with mayonnaise salad and garnish with parsley leaves.