Spicy Mango Hot Dogs with Crunchy Fried Onions

Name: Spicy Mango Hot Dogs with Crunchy Fried Onions
Ingredients: 1 1/2 cups finely diced mango; 2 tablespoons finely diced red onion; 2 teaspoons rice vinegar; 2 scallions, white and light green parts only, thinly sliced; 1/2 English cucumber, peeled, seeded and finely diced; 1/2 jalapeno, minced; Kosher salt and freshly ground black pepper; 8 hot dogs, butterflied; 8 brioche hot dog buns; Unsalted butter, at room temperature, for brushing the buns; 1/2 cup mayonnaise; 1 cup crunchy fried onions