Preheat oven to 350F.
In a large bowl, sift flour, baking soda and salt together. Make sure they’re really well blended, then add the lemon zest and combine.
Cream the butter and sugar until light, fluffy and getting pale.
Beat in the eggs one at a time, then add the lemon juice.
On a low speed, alternate adding flour and yogurt until both are gone, and the batter is just combined.
Remove the bowl from the mixer, and carefully fold the blackberries into the batter.
Grease your bundt pan (do this really well – depending on your bundt pan, you make butter it and then sprinkle a little flour, or simply use a cooking spray)
Pour the batter into the prepared bundt pan.
Bake for 1 hour, to 1 hour 10 minutes, or until a toothpick inserted into the center of the cake comes out clean.
Allow to cool in the pan, then flip out onto a wire rack to cool.