Final answer:
Senora Oralia might have laughed at the idea of a vegan tres leches because it is a traditional dessert heavily reliant on dairy, and making it vegan requires significant alteration to a classic recipe, representing a humorous or unexpected change in her eyes.
Step-by-step explanation:
Senora Oralia likely laughed when she heard that her daughter was cooking vegan tres leches because tres leches is a traditional Latin American dessert that is known for its decadent use of three kinds of milk, which are integral to its identity and flavor. By definition, a vegan version would omit these key dairy ingredients, replacing them with plant-based alternatives. This deviation from tradition might have seemed amusing or ironic to Senora Oralia, possibly because it suggests a twist on a beloved classic that is hard for her to envision, or perhaps it reflects a generational gap in attitudes towards traditional cuisine and modern dietary preferences.