Make the ranch: Combine aioli, sour cream, buttermilk, dill pickle, 1 1/2 tbsp. dill, the parsley, chives, celery salt, onion powder, garlic powder, black pepper, and salt in a medium bowl and mix until incorporated.
In a separate bowl, combine 1/2 cup ranch, the hot sauce, and 1 tbsp. dill. Mix together and set aside.
Heat a 12-in. cast-iron skillet over high heat. Add the oil and let the pan heat until wisps of smoke appear.
Add peppers to skillet and season with salt to taste. Do not move peppers for at least 1 minute to allow them to blister. Toss peppers and cook for another 30 seconds to 1 minute.
Place peppers on a serving platter and top with the remaining 1 tbsp dill and a few spoonfuls of spicy ranch.