- 1 cup cooked, cooled and mashed Japanese yam
- 1/2 cup tapioca starch or arrowroot starch
- 1/4 tsp sea salt
- 1 tsp finely chopped fresh rosemary
- 4 to 6 slices prosciutto
- 1 tablespoon duck fat, bacon fat or lard, divided
- Preheat oven to 375 degrees. Line a baking sheet with parchment paper.
- In a bowl, combine mashed sweet potato (ensure no lumps) with sea salt in a bowl.
- Mix in ¼ cup of the tapioca or arrowroot starch at a time. The mixture should form a thickened ball of dough.
- Transfer dough onto the baking sheet. Use your hands to roll out dough into a rectangle about ¼ inch thick. You can use parchment paper to assist you with this.
- Sprinkle rosemary evenly on the top surface of the dough. Layer prosciutto slices on top of dough.
- Roll the dough into a log shape, starting with one of the short sides and using the parchment paper to assist you.
- Brush dough with ½ tablespoon duck fat. Bake for about 30 minute until lightly golden brown. Brush with remaining 1/2 tablespoon fat.
- Turn oven broiler on high. Place baking sheet 6 inches away from the broiler. Broil stromboli for 2-3 minutes until medium golden brown. Watch carefully so you don’t burn the top! Let cool for a few minutes. Slice in half and serve immediately.
Best results will be achieved when using Japanese yam which is a purple skinned, white fleshed starchy sweet potato. You may try using Hannah variety white sweet potato which are slightly less starchy. Some people have used orange sweet potatoes but I don’t recommend them because they are sweet in flavor and not as starchy.