In a large bowl, whisk together all-purpose flour, rice flour, sugar, baking powder, salt, and baking soda.
Wet ingredients
3 In a blender or food processor, combine sour cream, milk, melted butter, chopped yellow pepper, and eggs. Blend until smooth (a few small flecks of pepper are fine).
Mix batter
4 Pour blended mixture into dry ingredients and whisk until just smooth.
Bake
5 Pour batter into prepared dish. Bake 30–35 minutes, until golden around edges and center springs back when pressed.
Cool & serve
6 Let cool 15 minutes before slicing.