Lay walnuts on baking sheet & warm in 350 degree oven for about 15 minutes. Remove & set aside.
Mix sugar & salt in small bowl & set aside.
Stir syrup, water & olive oil together in 2 qt saucepan - bring to a boil
Add walnuts & stir until nuts are coated
Continue to cook & boil until the nuts have absorbed all the liquid- about 5 minutes
Transfer to large bowl & add sugar/salt mixture - toss to coat
Pour out on parchment lined baking sheet & sprinkle with additional sea salt if desired.
Allow to cool & set before transfering to airtight container.
Store at room temperature