In a large bowl, combine the flour, cornmeal, sugar, baking powder, salt and chili powder. In a small bowl, beat the eggs; add milk, oil, onion and chilies. Stir into dry ingredients just until moistened.
Fill greased or paper-lined muffin cups two-thirds full. Bake at 400° for 20-25 minutes or until muffins test done. Serve warm.