In large saucepan, heat olive oil over medium-high heat. Add onion and celery; cook, stirring constantly, 2 to 3 minutes, or until onion is translucent.

Stir in tomatoes, 2 cups water, beans, bacon, oregano, red pepper flakes, if desired, and contents of Spice Sack. Bring to a boil.

Stir in couscous; cover. Remove from heat. Let stand 5 minutes.

Gently stir before ladling into bowls. Serve with crusty Italian bread and top with grated Parmesan cheese, if desired.