I think she's holding her vulva, in a way to make it look like a sandwich. The right side of the "bun" is connected, and there's (shaved) pubic hair there. Also the highlights give the area a slick and fleshy look that doesn't really fit bread.
Removing artist_request tag, since the artist isborusen, looking at the Pixiv link provided by both kuroxxx95 and Saucenao. I'm not sure where the confusion was but it definitely is borusen.