Heat oil in a 6-quart pressure cooker over medium-high heat. Add onion, and sauté 2 minutes. Remove casings from sausage. Add sausage to cooker; cook 2 minutes, stirring to crumble. Add eggplant and next 9 ingredients (eggplant through tomatoes). Close lid securely; bring to high pressure over high heat. Adjust heat to medium or level needed to maintain high pressure; cook 4 minutes. Remove from heat; place cooker under cold running water. Remove lid, and stir in raisins and thyme. Serve over couscous; sprinkle with cheese.