In medium bowl, mix vinegar, sugar and 1 teaspoon salt. Add carrots and cucumber. Cover and refrigerate until ready to assemble sandwiches.
Heat oven to 375°F. Line 15x10x1-inch pan with foil. Spray with cooking spray.
In large bowl, stir meatball ingredients until well mixed. Shape into 30 (1-inch) balls; place in pan.
Bake 25 to 30 minutes or until meatballs are no longer pink in center.
Meanwhile, in 3-quart saucepan, stir sauce ingredients until well blended. Heat to boiling over medium heat. Reduce heat to low; simmer 5 minutes, stirring occasionally. Add hot meatballs to warm sauce; stir to coat.
To make each sandwich, cut each baguette into 3 (6-inch) pieces. Split each piece in half. Place meatball mixture on bottom half of each baguette piece. Using slotted spoon top with carrot-cucumber mixture. Add cilantro sprigs And jalapeno slices to taste; place over with baguette tops.