Turtle makes Taylor the "main ingredient" in her vegetable soup song because Taylor is the most important person in her life. Taylor has been taking care of Turtle since she was a baby, when Turtle's aunt begged Taylor to take her. Turtle was abused before she came to live with Taylor, and she has a hard time trusting people. What gives Turtle the most pleasure is plants--flowers, vegetables, all plants. Her adding people's names into her song about vegetable soup is an indication that she is beginning to open up and let people into her world. The fact that Taylor, her foster mother, is the main ingredient is a sign that Turtle has bonded with her and thinks of her as a mother.