With pressure cooker set to saute, heat oil over medium low heat. Add leeks and sauté until soft, about 4-5 minutes; add garlic, and bell pepper and sauté about 2-3 minutes. Add corned beef, peppercorns, bay leaves, parsley and water; cover and set cooker to high pressure for 55 minutes. Use natural pressure release. Remove the corned beef, set it on a cutting board and shred with a fork. Return it to the pot then add the stock, cabbage, carrots and potatoes, taste for salt and pepper and adjust as needed. Set cooker to high pressure for 4 minutes. Let set for 20 minutes after finished then release rest of pressure with quick pressure release.