Coat walnuts in walnut oil and a sprinkle of flaked sea salt. Bake at 350°F for approximately 8 minutes until golden. Watch carefully as they do burn easily, and walnut oil turns bitter if heated too high.
Combine all of the other ingredients except the feta and heat in a saucepan on low heat (approximately 170°F) for 1 hour.
Allow to cool completely at room temperature or in the refrigerator. Remove the lemon peel and sprigs of fresh rosemary and thyme.
Break the cheese into roughly ½-inch pieces and place in a glass storage jar with a lid. Add the roasted walnuts and additional fresh lemon peel, rosemary and thyme for garnish. Pour the thoroughly cooled oil mixture over the cheese.
Allow to marinate at least 1 hour before serving. The longer it marinates, the deeper the flavor. Stored in the refrigerator, this cheese should keep for at least a week.