My friend have a stomach ulcer I want to help her. What foods should not be cooked? No vinegar, right?

Ulcers. Generally acidic foods like vinegar, wine, oj, lemon juice, lime juice, tomatoes as well as spicy foods, fried/fatty foods, caffeine/coffee & soda pop exacerbate ulcers. Even milk should have as low fat content as person can tolerate. Hopefully she is taking medication to help heal the ulcer; then she will gradually be able to eat the foods she enjoys again.