I make these almost every week. And not long ago sweet potatoes were only $0.29/lb at Publix which was the greatest thing that happened to me in 2009, only second to Stephen Small's birth! Seriously, I've never known anything to be so cheap in my lifetime.
First, pre-heat oven to 400 degrees. Then dice sweet potatoes in french fry like shapes making them all about the same size so they cook evenly. As far as serving size...one sweet potato per person is a nice ratio.
Spread them out on a cookie sheet. Then drizzle with olive oil and coarse salt...sea salt, kosher salt, etc. Give them a toss to make sure each fry is coated well with olive oil.
Next, cook in oven for 15 minutes. Then remove and flip them to the other side and cook for an additional 15 minutes. This prevents them from getting too brown on one side.
Last, remove from oven and throw a fresh herb on top....I like parsley. It adds a nice flavor and color.
Let your sister try the first one because they are H-O-T hot and YUM.
We like ours best dipped in homemade honey mustard. I make them with sandwiches, burgers...everything!