Place lentils and bay leaves in a large saucepan. Cover with water to 2 inches above lentils; bring to a boil. Reduce heat, and simmer 18 minutes or until tender; drain. Discard bay leaves.
Heat a large nonstick skillet over medium-high heat. Add pancetta; sauté 2 minutes or until browned. Remove the pancetta with a slotted spoon. Add cabbage to drippings in pan; sauté 5 minutes or until tender. Combine the lentils and cabbage in a large bowl. Combine vinegar and the remaining ingredients, stirring with a whisk. Drizzle vinaigrette over lentil mixture; toss well to coat. Sprinkle with pancetta just before serving.