To make the batter, sift the flour into a bowl and stir in 1/4 teaspoon salt. Mix in the oil with a wooden spoon . Slowly add 80-125 mL (1/3- 1/2 cup) warm water, changing to a whisk when the mixture become liquid. Continue whisking until the batter is smooth and thick. Whisk the egg whites until stiff peaks form, then fold into the batter.
Check the zucchini flowers are clean and aren't hiding any stray insects. Trim the stem of each flower to 2 cm, to give you something to hold on to when dipping.
Heat the oil in a deep-fat fryer or deep frying pan about 350 degrees Fahrenheit (180 degrees Celsius), or until a piece of bread fried golden brown in 15 seconds when dropped in the oil. If the oil starts to smoke, it is too hot.
Dip the zucchini flowers into the batter, coating both sides. Fry the flowers in batches until golden brown, turning once to cook on both sides. Drain on paper towel and serve with a sprinkling of salt and a lemon wedge. Don't let them sit around- serve and eat immediately, preferably with a glass of chilled wine.