Preheat oil or fryer to 350 degrees.
In a mixing bowl, combine buttermilk, vegetable oil, and eggs; mix well.
In a separate mixing bowl, combine cornmeal, flour, sugar, baking soda, fennel seed, mustard, salt, and garlic powder; mix well.
Mix the dry ingredients with the wet ingredients.
Add the onion and jalapeno to the mixture and fold until evenly distributed.
Using a small ice cream scoop, carefully, drop a scoop of the batter into the oil (do this few at a time until you get the hang of it). Cook each one for about five minutes or until they have a nice brown, crispy, crust.
Place on paper towel to soak up some of the extra oil.
Do a sample cook on one to test the doneness, adjust accordingly.