Heat oil in a large Dutch oven over medium heat. Add onion to pan; cook 4 minutes, stirring frequently. Add sugar and next 7 ingredients (through fennel seeds); cook 1 minute, stirring constantly. Stir in vinegar; cook 30 seconds. Add broth and tomatoes; bring to a simmer. Cook over low heat for 55 minutes or until sauce thickens, stirring occasionally. Yield: about 12 cups (serving size: 1/2 cup).