I believe the "tortilla star" is an example of synechdoche, a figure of speech whereby a less comprehensive term is used to indicate a more comprehensive one. In this case, the "tortilla star" is a play on the conventional term "morning star", by which people are awakened. The substitution of "tortilla" for "morning" gives the original word an ethnic element, conveying the author's point that Alicia must rise very early each day because of cultural obligations she cannot escape. The "tortilla" is symbolic of the familial duties Alicia must fulfill as an Hispanic woman in a patriarchal family. Although Alicia is intelligent and has dreams of bettering herself through education, her aspirations must take a backseat to her family's needs. Since her mother is dead, she must rise early each day to make "the lunchbox tortillas" for her father and younger siblings. Her culture dictates that it is "a woman's place" to "wake up early" and care for the family and the home.