I make oven fries even though we have a deep fryer. Cut potatoes the same thickness as Mcd's, soak in water for an hour, drain and let dry a little, melt butter just until soft liquid, combine the salted butter and fries in a large mixing bowl and toss to ensure they are coated. Bake at 400 on a cookie sheet til golden brown, then salt with fine salt(not table salt) to taste. Enjoy!
You can also add truffle oil, fresh minced parsley, parmesan cheese and coarse sea salt. You can also experiment with smoked sea salts.
Another option is to serve with fresh garlic aoli.
If you insist on deep frying I suggest using peanut oil. Awesome flavor!
Now sweet potato fries are a whole nother story!