Preheat the oven to fan assisted 160C / 180C / 350F / gas 4 and lightly oil a two 6 cup doughnut trays.
Mix together the flour, sugar, baking powder and salt in a large bowl and set aside.
In a smaller bowl, combine the buttermilk, eggs and Fentimans sparkling lime and jasmine before adding in the cooled melted butter.
Mix the wet ingredients into the dry ingredients and stir until just combined.
Using a spoon, add the batter into 8 doughnut cups until they are three quarters full.
Bake the doughnuts for 13-15 mins until a toothpick comes out clean, remove them from the oven and let them cool in the pan before transferring them to wire rack to cool completely.
Make the glaze when the doughnuts are cool. Add the icing sugar and 1 tbsp of Fentimans sparkling lime and jasmine into a bowl and whisk with a fork to combine. Add another tbsp of Fentimans sparkling lime and jasmine as necessary so you end up with a thick but dipable glaze.
Dip the doughnuts into the glaze, top with dried rose petals and allow the glaze to set for 30 mins before serving.