Avi says:
“This is the way the old woman killed people”
The old woman mixes soup for her intended (male) victims using pieces of her own brain. As the brain is the seat of consciousness, it might be assumed in this context that such a mixture would render its consumer “unconscious” of his former self. In other words, he would cease to be a “man”, having eaten of women’s brains, and might begin to adopt a feminine consciousness, thereby obliterating his own.