Heat oven to 450° F (A very hot oven! Be sure your oven is clean or you will have a very smoky kitchen.)
Pluck the rosemary leaves from the stem then tear the rosemary leaves into a medium-sized bowl.
Wash and dry the potatoes. Cut the potatoes in half then cut lengthwise into 2 cm wide wedges.
Place wedges in a bowl and add the rosemary, olive oil and sea salt. Toss the potatoes until evenly coated.
Place the potato wedges in a single layer on a parchment-lined cookie sheet (or greased cookie sheet).
Place in the hot oven for 15 minutes. After 15 minutes, have an adult carefully remove the tray from the oven. Flip the fries over with a pancake flipper. Return to the oven for 15 to 20 minutes, or until tender.