Courgette flowers are usually not available in large amounts so it's a good idea to fry courgette and their flowers together. I make a simple beer batter from flour and cold beer; the bubbles give it a nice crisp.
Remove the stems from the courgette flowers and place in a bowl of cold water for 1 hour. This way they will keep fresh and crisp. Drain and gently pat dry perfectly.
In a bowl place the flour and pour the beer, a bit a the time, stirring with a fork until you get a smooth and lump-free batter. Add salt.
Heat about 5cm olive oil in a frying pan till it sizzles. Dip the courgettes and courgette flowers in the batter one at a time. Fry in batches, a few at the time, turning them gently to cook evenly. Remove with a slotted spoon and drain on paper towel.