Preheat the oven to 325 degrees. Spread nuts on a small rimmed baking sheet, and bake until fragrant and beginning to brown, 10 to 15 minutes. Remove from oven, and let stand until cool. Coarsely chop; set aside.
Line a baking sheet with a Silpat (a French nonstick baking mat); set aside. In a medium stockpot, heat oil over high heat. Add popcorn, and cover. Once the corn begins to pop, shake the pan constantly. When the corn has finished popping, remove from the heat, uncover; set aside.
In a large deep pot, at least 12 inches wide, stir together water, sugar, and corn syrup. Add vanilla pod and seeds, cinnamon, nutmeg, cloves, cardamom, and salt. Bring to a boil over medium-high heat without stirring. Using a pastry brush dipped in water, brush down the sides of the pan to remove any undissolved sugar granules. Reduce heat to medium, and cook, tilting and swirling the pan, until the mixture just begins to smoke and is a deep caramel color, 4 to 5 minutes more.
Stir in the popcorn and nuts. Cook, stirring, while moving the pot on and off the heat to prevent the caramel from burning, until the popcorn is completely coated and the mixture is deep mahogany in color. Pour onto prepared baking sheet, and spread in an even layer. Let cool. Remove and discard vanilla bean. Store in an airtight container at room temperature for up to 3 days.