Preheat the oven to 400 degrees Fahrenheit.
Cut the sweet potatoes in half, lengthwise.
Place one of the sweet potato halves on a cutting board and lay stainless steel straws, wooden spoons, or chopsticks on either side of the sweet potato (see the picture above in the post).
Make small, even slices on the sweet potatoes, as close together as you are able to, using the steel straws (or wooden spoons or chopsticks) to stop you from cutting all the way through the sweet potato.
Repeat with the other sweet potatoes.
Place the sweet potatoes on a sheet pan lined with parchment paper.
In a small bowl, add the extra virgin olive oil, thyme, sage, rosemary, salt, and pepper and stir to combine.
Brush the sweet potatoes with the olive oil and herb mixture.
Bake for 1 hour or until the bottoms of the sweet potatoes are dark golden brown but not burnt, pausing to baste the sweet potatoes with more of the oil mixture every 20 minutes.