In bowl, toss julienned carrots with rice vinegar, salt and sugar. Let sit while you heat meatballs and assemble the sandwiches.
Heat meatballs on medium-high in skillet for 7-10 minutes or until hot all the way through.
In small dish mix mayonnaise and siracha together. Spread on to each baguette and then stuff with meatballs, cucumber, pickled carrots, and fresh cilantro.