Preheat your oven to 350°F. It’s important to have the oven ready before you start baking to ensure even cooking.
Spray an 8X5-inch loaf pan with nonstick spray to prevent the bread from sticking.
In a medium bowl, whisk together the first five dry ingredients: flour, baking powder, baking soda, and salt. This step helps distribute the leavening agents evenly throughout the flour.
In a large bowl, use an electric mixer to combine the butter and both sugars. Beat them together for about two minutes until the mixture is light and fluffy. This aeration will help create a lighter texture in your bread.
Add the eggs, sour cream, lemon zest, and vanilla to the butter mixture. Beat until all the ingredients are combined and smooth.
Mix in the mashed bananas and strawberries, stirring gently to combine without overmixing.
Gradually stir in the dry ingredients just until combined. Be careful not to overmix, as this can lead to a dense bread.
Gently scoop the batter into your prepared loaf pan, smoothing the top with a spatula.
Bake the bread for 55 to 65 minutes, or until a toothpick inserted into the center comes out clean. The bread should be golden brown on top.
Once baked, remove it from the oven and let it cool in the pan for about 10 minutes before transferring it to a wire rack to cool completely.