100²µ/3Β½΄Η³ϊ blueberries
1 unwaxed lemon, zest finely grated
4 tsp fresh lemon juice
1 tsp bicarbonate of soda
75g/3oz golden caster sugar
100²µ/3Β½΄Η³ϊ icing sugar
200g/7oz self-raising flour
50ml/2fl oz sunflower oil
2 free-range eggs
2 tbsp semi-skimmed milk
150ml/ΒΌ pint low-fat natural yoghurt