Heat your oven to 450℉ and then slice the potatoes into fries about ⅓ inch think.
Fill your sink with water and soak the fries in it for at least 20 minutes (this removes the starch which helps the fries get crispy)
Strain the fries in a colander and then dry with a kitchen towel. The more dry your fries are, the crispier they will get.
Place the fries in a large bowl, pour in some cooking oil and then toss to coat. You don't need a lot of oil, just enough to coat the fries. Probably about ¼ cup.
Spread the fries out across 2 large parchment lined baking sheets. Try where possible to have the fries not touching each other.
Bake in the oven for 20-25 minutes, taking them out once after 15 minutes to check on them and turn the fries.
For the sauce:
Combine the sour cream, garlic powder, onion powder, salt and parsley