The ingredients need to be at room temperature due to the mixing technique, so make sure to bring the eggs and yogurt to room temperature first. I recommend setting the whole eggs in warm water for a few minutes.

Preheat oven to 350 degrees F. Grease a loaf pan with at least a 6 cup capacity (8 ½ by 4 ½ or a 9x5 inch) and line with a strip of parchment. Grease again and dust with flour because the berries can be sticky.

Combine the flour, baking powder, baking soda, salt, cornmeal and sugar in a large mixing bowl and whisk for about a minute, making sure everything is evenly distributed.

Add the blackberries and raspberries to the flour mixture and carefully stir so that the berries are coated in dry mixture.

In another mixing bowl, whisk the eggs lightly, then whisk in the yogurt, vanilla and lemon zest until smooth. Whisk in the melted butter, stirring just until blended and smooth.

Combine the dry ingredients with the wet ingredients, and with a large heavy duty rubber scraper, fold everything together until well blended. Spoon and scrape the batter into the prepared loaf pan.

Bake for about 45-60 minutes (loaf pan will influence the cook time -- my glass pan took about 70 minutes) or until the loaf is golden and a skewer or toothpick comes out clean and the internal temperature is 200 degrees.

Let cool on a rack for 20 minutes, then loosen sides with a knife and jiggle the strip of parchment paper. If the bread feels solid enough to lift, remove it from the pan and let cool on the rack. If it still feels delicate, let it cool completely in the pan.

Slice the bread when it is completely cool.