Preheat oven to 350 F. Spray a loaf pan with non stick spray.
In a large bowl, combine flour, baking powder, baking soda and cornmeal.
Using a whisk or wooden spoon, stir to remove any lumps.
Using an electric mixer, combine eggs, yolk, lemon zest, salt and sugar. Beat well for about 5 minutes on high speed until light in color, barely yellow and doubled in volume.
In a small bowl, whisk together lemon juice and oil until thoroughly combined.
Add lavender and half of the flour mixture and then half of the lemon mixture, mixing well after each addition. Repeat.
Transfer to prepared loaf pan.
Bake for 50-60 minutes, until knife inserted comes out clean.
Leave to cool for 10 minutes before removing from pan.
Cool completely and slice.
Notes
Use fresh lemon juice. Bottled lemon juice won't yield the same flavor!