Preheat oven to 350°F.

Mix chopped kumquats with flour, baking powder, salt and sugar.

Separately, stir together the cooled melted butter, buttermilk, orange juice, vanilla and eggs.

Combine the wet and dry ingredients just to combine, but do not overmix.

Fold in the dried blueberries.

Divide batter among greased muffin cups and sprinkle with sugar and extra blueberries.

Bake for 20-25 minutes or until a toothpick has no wet batter on it.

Cool in pan 5-10 minutes, then turn out and continue to cool on a wire rack.