In a small saucepan over medium heat, combine apple cider vinegar, water, sugar, and salt. Stir until the sugar and salt dissolve, about 1-2 minutes. Place the thinly sliced red onions in a heatproof jar or bowl, then pour the hot vinegar mixture over them. Let them sit at room temperature for at least 20 minutes while you prepare the tacos.

Preheat your oven to 375°F (190°C) and line a large baking sheet with parchment paper or foil for easy cleanup.

In a large bowl, mix the shredded chicken with buffalo sauce, sour cream, and blue cheese dressing until well combined.

Lay the flour tortillas flat and sprinkle about ¼ cup shredded cheddar cheese in the center of each one. Microwave the tortillas for 10–15 seconds to soften them slightly. Wrap each cheesy tortilla around a crunchy taco shell, pressing gently to help them stick together.

Place the assembled shells seam-side down on the prepared baking sheet. Evenly distribute the buffalo chicken mixture inside each crunchy taco shell. Bake for 8–10 minutes, or until the tortillas are golden, the cheese is melted, and the taco shells are warm and crispy.

Once out of the oven, open each taco slightly and top with sliced fresh jalapeños, pickled red onions, sliced scallions, and thinly sliced radishes.

Serve immediately while warm. Pair with extra buffalo sauce or a side of ranch for dipping!