Combine 1 cup sugar, the vanilla pod, cinnamon, allspice and nutmeg in a large bowl. Work the vanilla seeds into the mixture with your fingers until incorporated; set aside.
Beat the remaining 1/4 cup sugar, the egg yolks, bourbon and vanilla extract in a medium bowl with a mixer on medium-high speed until light and creamy, about 2 minutes. Beat in the flour and salt in 2 batches, alternating with the sour cream, until just combined. Continue beating until the dough starts to pull away from the side of the bowl, about 3 minutes (it will be sticky). Turn out onto a floured surface and knead until smooth and elastic, about 5 minutes. Cover with plastic wrap; let sit at room temperature 30 minutes.
Line a baking sheet with parchment paper. Cut the dough in half; roll out each half into a thin 9-inch square on a floured surface. Cut each square into 1-by-3-inch strips. Cut a 1-inch slit lengthwise in the center of each strip; insert one end of the strip into the opening, pull through and twist to make a bow tie shape. Transfer to the prepared baking sheet.
Set a rack on another baking sheet. Heat 2 inches vegetable oil in a large pot until a deep-fry thermometer registers 350 degrees F. Working in batches of 6 to 8, fry the cookies, turning once, until golden brown and crisp, 3 to 4 minutes. Transfer to the rack with a slotted spoon; toss in the spiced sugar while still warm.