Preheat the oven to 375°F. Grease and flour a 12-cup muffin pan, or line with papers. Mix together the butter, granulated sugar, and the brown sugar, beating until fluffy. Add the egg and mix well, stopping once to scrape the sides and bottom of the bowl. Gently mix in the yogurt. Stir in the flours, baking powder, baking soda, salt, and zest.
Fold in the chopped strawberries and chocolate chips, if using. Divide the batter evenly among the prepared muffin cups.
Bake the muffins for 25 to 30 minutes, or until a toothpick inserted into the center of a muffin comes out clean.
Remove the muffins from the oven, cool them for 5 minutes in the pan, then turn them out onto a rack to finish cooling completely. Dust with powdered sugar.