Preheat your oven to 375°F.

Line a muffin pan with paper liners or grease the cups with cooking spray.

In a large mixing bowl, whisk together the flour, sugar, baking powder, baking soda, and salt until well combined.

In a separate bowl, mash the ripe banana using a fork until smooth.

Add the Greek yogurt (or sour cream), melted butter, egg, and vanilla extract to the mashed banana, and mix until smooth and well combined.

Pour the wet ingredients into the dry ingredients and gently fold together using a spatula until just combined. Be careful not to overmix, as this can result in dense muffins.

Gently fold in the diced strawberries until evenly distributed throughout the batter.

Spoon the batter into the prepared muffin cups, filling each about 2/3 full. Add chopped strawberries to the tops of the muffins.

Bake in the preheated oven for 18-20 minutes, or until the muffins are golden brown and a toothpick inserted into the center of a muffin comes out clean.

Allow the muffins to cool in the tin for a few minutes before transferring them to a wire rack to cool completely.