Heat the oil in a heavy-based pan until a breadcrumb sizzles.
Mix ricotta, lemon zest, and juice in a bowl and season.
Spoon the ricotta mixture into the courgette flowers without overfilling.
Squeeze the petals together to enclose the filling.
Dredge each flower in plain flour.
Mix flour, bicarbonate of soda, and salt in a bowl.
Whisk in 250ml of carbonated water to form a batter.
Dip flowers in batter and deep-fry for 3-4 minutes until golden.
Drain flowers on kitchen paper.
Mix mint, lemon juice, and crème fraîche in a bowl.
Stir in the sliced fennel to coat.
Serve the flowers on top of the fennel salad.