Create the batter.
Add 1 cup of sour cream to the 200g of softened butter and begin to blend the two. As you do this, mix in the 1.5 cups of sugar and both eggs. Blend everything until the sugar is largely dissolved and everything is coming together in a consistent mass.
At this point, take half of teaspoon of bicarbonate soda and place it into a clean table spoon. Holding the tablespoon over the mixture, add some white vinegar to the spoon. The goal here is to activate the baking soda and have ti foam off the spoon. So don’t drown the spoon but only add as much as you need to set off the reaction with all of the powder. Mix this into the liquid consistently.
Then, gradually begin to add in the flour as you continue to mix. When you are done, you should have a batch of batter as pictured here. It is neither runny nor dough-like here you can knead it.