Preheat oven to 375F (190C) and grease 3 12-cup mini muffin tins. Sift cornmeal, flour, sugar, baking powder, and celery salt into a bowl. Stir in chives and coriander. In a separate bowl, whsk buttermilk and oil. Add buttermilk mixture to dry ingredients; stirring just until incorporated (do not overmix). Divide batter equally among prepared muffin cups. Bake muffins until tester inserted into center comes out clean, about 8 minutes. Cool for 10 minutes, then turn out to cool completely.