How to gently let my roommate know that I care about others eating from my bowl?

When eating, my roommate will come straight up to me, put her hand directly into my bowl (the point is, use her hand, no matter what she touched with her hand before), pinch away a piece of meat or vegetables, or something else, regardless of my obvious nausea ... smile manually. The point is that when I was angry, she still thought it was our intimate performance ... smiling manually again. As for the solution ... "How to let roommates know euphemistically", why euphemistically? Can you do it directly? Anyway, my solution is to isolate her All right, isolate her and shake her face. Now the world is clean.