Preheat oven to 400 degrees; grease a baking sheet. Combine the flour, cheese, baking powder, oregano and salt in a large bowl or food processor. Cut in the butter with a pastry blender, 2 knives or pulses of the food processor until the mixture resembles coarse crumbs. If blended in a food processor, transfer the mixture to a large bowl. Combine the milk, eggs and Tabasco sauce in a small bowl until well blended; stir into the flour mixture just until moistened. Stir in the onion. The dough will be sticky. Place the dough onto the center of the baking sheet; pat the dough into a 9-inch circle. Cut into 8 wedges. Bake for 20 to 25 minutes, or until golden brown and a toothpick inserted in the center comes out clean. Remove from the pan. Cool on a wire rack for 10 minutes.