Mochi Banana Bread

Name: Mochi Banana Bread
Ingredients: 90 grams (2/3 cup) glutinous rice flour, like Mochiko; 40 grams (1/3 cup) all-purpose flour; 1/2 teaspoon baking powder; 1/2 teaspoon baking soda; 1/2 teaspoon kosher salt; 1 medium to large banana, ripe (about 110 grams peeled); 90 grams (scant 1/2 cup) granulated sugar; 55 grams (1/4 cup) light brown sugar; 113 grams (1/2 cup/1 stick) unsalted butter, melted and cooled; 60 grams (1/4 cup) full-fat sour cream, at room temperature; 1 large egg, at room temperature; 1/2 teaspoon vanilla extract; Chopped toasted walnuts and/or toasted coconut, for topping (optional)