Preheat oven to 375 degrees . Line baking sheet with parchment.
Keeping the root end intact, peel onions; then cut each into 4 wedges, through the root.
Wash and dry potatoes. With a chopstick along each side so slices stay connected at the bottom, cut into 1/8 to 1/4 inch slices.
Place each potato and onion wedge into a bowl with sesame oil, brushing oil into spaces between slices. Arrange on a parchment-lined pan.
Bake 30 minutes; remove from oven, and brush liberally with your favorite Zena's SASS. Return to oven, bake 30 minutes more, ‘til fork tender. The potatoes and onions will begin to ‘blossom.’ Brush with SASS one last time, and return to oven 5 minutes.
Transfer to a warmed platter or shallow bowl to serve.