Place vinegar in a small, heavy saucepan; bring to a boil over medium heat. Cook until slightly syrupy and reduced to 1 tablespoon (about 4 minutes). Set aside.
Bring broth to a simmer in a medium saucepan (do not boil). Keep warm.
Heat 1 tablespoon oil in a large saucepan over medium-high heat. Add leek to pan; sauté 3 minutes or until tender. Add rice; cook 2 minutes, stirring constantly. Stir in wine, and cook 1 minute or until liquid is nearly absorbed, stirring constantly. Stir in 1 cup broth; cook 5 minutes or until liquid is nearly absorbed, stirring constantly. Reduce heat to medium. Add remaining broth, 1/2 cup at a time, stirring constantly until each portion of broth is absorbed before adding the next (about 25 minutes total). Stir in half-and-half, salt, and pepper; cook 2 minutes. Remove from heat; stir in tomatoes, basil, and cheese. Place about 1 cup risotto into each of 6 shallow serving bowls; drizzle each serving with 1/2 teaspoon balsamic syrup and 1/2 teaspoon oil.