Zest the lemon and rub the zest with sugar to extract the essential oils from the lemon peel
- Add the butter to the sugar and start mixing 
- Add the vegetable oil and continue whisking
- Add the eggs gradually with the vanilla 
- Add lemon juice and continue whisking
- At this stage, we stop using the electric mixer, add half the amount of dry ingredients to the egg mixture, and begin mixing in one direction using the spatula.
- Add the yogurt to the mixture and continue stirring using the spatula
- Add the second part of the dry ingredients and stir until the mixture is homogeneous
- Add a spoonful of flour to fresh or frozen berries and coat them well with flour before adding them to the mixture.