Begin heating the shortening or oil in a deep-fryer or cast-iron skillet over medium heat.
In a large bowl, stir together the cornmeal, flour, baking powder, baking soda, coriander, chili powder, and cayenne. Stir in the grated onion. Stir in the buttermilk, eggs, and corn until combined. The mixture will have the consistency of wet sand.
Heat the oil until it registers 375 degrees F on a deep-fat thermometer. (You can also test the heat by sprinkling a bit of cornmeal on the hot oil to see if it bubbles.) Scoop up rounded tablespoons of dough and carefully drop them into the fat (in batches, if necessary). Fry on one side until golden, 2 to 3 minutes. Turn and fry the other side until completely golden. Using a slotted spoon, transfer the cooked hushpuppies to several layers of paper towels to drain. Serve immediately.
Recipe adapted from The New, Low-Country Cooking (William Morrow, 2000) by Marvin Woods