2) Something that's often worked for me is simply learning to prepare and cook the food item myself. (Even more so if I can first grow it or catch it myself, where possible.) You can learn to taste when something is properly cooked even if you don't think you like that taste, and then it's only a short path from "tastes properly cooked" to "tastes delicious!"

I think this could work particularly well in combination with JMG's advice.