In a bowl, mix together the pork, basil, garlic, onions, fish sauce, sriracha, sugar and salt and pepper and mix it all up with your hands. Roll into 1" balls and place on a rimmed baking sheet. Bake at 400F for 20 minutes, or until golden and cooked through.
Meanwhile, toss the grated carrot with the rice vinegar and sugar in a small bowl. Let sit until you're ready to assemble your sandwiches.
To assemble, spread baguettes with mayo; top with a squirt of sriracha to taste, and stuff with pickled carrots, cucumber strips, meatballs and sprigs of fresh cilantro.