Mix the fresh yeast, flour, and water until it's the consistency of pancake batter.
Allow to sit and fluff up for half an hour at room temperature.
Cut the mozzarella into pencil-thick, 2 inch strips
In the meantime clean the zucchini flowers: remove stamen & pistil from inside the flower with your index finger, then carefully rinse and drain on paper towels.
Just before frying stuff each flower with a strip of mozzarella and an anchovy fillet.
You can use another filling if you prefer. Some ideas are: cooked chicken, mozzarella and tomato, fresh figs and Gorgonzola, or no filling at all.
Dip in the batter and deep fry until just crisp.
Drain on paper towels, salt and serve immediately.