Go early, walk one full loop before buying anything, and notice what people are carrying home. Ask before photographing vendors or stalls closely.
Use one ingredient as a guide
Choose an unfamiliar fruit, spice, noodle, or prepared dish and ask your hotel or a local host how it is usually eaten. One detail can open a whole meal.
Mind food handling
Use common sense with temperature and hygiene, especially for raw or ready-to-eat items. Choose busy stalls where turnover is visible.