Preheat the oven to 160° C. Grease a non-stick coated pan measuring approx. 23 x 13 x 6 cm.
Mix flour, baking powder, baking soda and salt together in a small bowl and set aside.
Add 1 tablespoon of the flour mixture to the blueberries until they are covered with flour and set aside if necessary. (If the flour doesn't stick because the blueberries are too dry, simply add ½ tsp lemon juice to the berries.) This step should prevent the blueberries from sinking downwards in the batter.
Beat the butter and sugar in a large bowl for about 1 minute until you get a fluffy, light, creamy mass. Add the eggs all at the same time and whisk together. Slowly stir in the flour mixture, sour cream, lemon peel and lemon safe in portions. Gently mix in half of the blueberries.
Pour the dough into the box pan. Sprinkle the other half of the blueberries on top. Bake the cake on the middle rack for 45 — 55 minutes. Test with a wooden stick whether the cake is already done: The dough is done when it no longer sticks to the stick.
After baking, let the cake cool in the pan for at least 30 minutes, then place it on a rack.
Here you can find some of the ingredients for the recipe