Cook pasta in large pot of boiling water following package directions.
Meanwhile, heat oil in large, deep, nonstick skillet over medium-high heat. Add onions; cook, stirring often, until very soft and golden brown, about 5 minutes. Add garlic; cook 1 minute. Remove from heat. Stir in vinegar, salt and pepper.
Drain pasta; toss with onions and Gorgonzola in large serving bowl.