Place a frypan over a medium heat. Add the oil, honey and cinnamon, followed by the walnuts. Use a spatula to move the nuts around the pan until they're all coated and there's not much liquid left in the oven, about 2 minutes. Transfer to a lined baking tray to cool, and sprinkle over some flakey sea salt while they're still hot. It adds a nice flavour contrast and some crunch.