Whisk together vinegar, sugar and salt until sugar and salt are dissolved.
Stir in carrots and cucumber. Let stand for 30 minutes, stirring occasionally.
Preheat grill to medium, then oil grates. Grill hot dogs until heated through, approximately 6 minutes, turning occasionally.
Whisk mayo and sriracha in a small bowl. Spread about 1 Tbsp. mayo mixture on buns, add hot dogs and top with carrot mixture.