01 -  Preheat oven to 300°F. Line a large baking sheet with parchment paper. 
 02 -  Place the popped popcorn in a large mixing bowl. Add the peanuts, mini pretzels, rice cereal squares, and pepitas or sunflower seeds. Toss gently to combine. 
 03 -  In a small saucepan over low heat, melt the butter. Stir in Sriracha, brown sugar, smoked paprika, garlic powder, and salt. Simmer, stirring until the mixture is smooth and sugar dissolves, about 2 minutes. 
 04 -  Pour the hot spicy sauce over the popcorn mixture. Toss thoroughly with a spatula or large spoon until contents are evenly coated. 
 05 -  Spread the mixture evenly on the prepared baking sheet. Bake for 10 minutes, stirring once halfway through, until dry and crisp. 
 06 -  Remove from oven and allow to cool completely before serving or storing in an airtight container.