Peeled and wash the potatoes clean. Pat dry with towel. Cut into about 1/2-inch thick stick, try to be uniform in size as much as you can. Soak the cut potato in cold water to prevent browning and continue cutting the rest. Let the potato soak in the water for about 1 hour or longer. This is the part where the starch will leech out from the potatoes and make them crispy
While the potatoes are soaking, mix the olive oil, with miso paste and rosemary leaves until well combined. Set aside
When ready to bake the potato, preheat the oven to 400 F. Drain the water off and pat the potato sticks dry with kitchen towel. As dry as you can so the oil and sauce coat them better. Line 2 baking sheets with parchment paper and spray with non-stick spray. I will not try to crowd the sheet as that will make your fry not crispy. Pour the sauce over and use your clean hands to tossed so they are well coated
Pop them into the oven and bake for about 35 minutes or longer or until they are golden brown and crispy. It took almost 45 minutes on my oven (but mine always take longer anyway, so know your oven!). Give them a little shake and turn them around half-way cooking
Remove from the oven and serve immediately. I don't feel there's a need to add anymore salt as the miso paste is salty enough, but you be the judge, season with more salt if you need