Gently pull the stamen out of each zucchini flower. Set the flowers aside.
Beat the flour, eggs, and salt together in a bowl until they are smooth. Beat in the milk. Set the batter aside.
Mix the mozzarella, capers, tomato and basil together and fill the inside of each zucchini flower with some of this mixture. Fold the ends of the petals over the filling to enclose it.
Heat the oil to a depth of 2 inches in a heavy saucepan or a wok.
Dip the stuffed flowers into the batter, allowing any excess to run off. Fry the flowers until they turn light gold, 6 to 8 minutes. Drain them on absorbent paper as they are done. Sprinkle them lightly with salt and serve them while they are warm.