Many restaurants in the United States that bill themselves as South Indian serve popular vegetarian snacks from neighboring Tamil Nadu rather than Keralan dishes. To identify authentic Keralan food on a menu, look for the word Malabar, Kerala's coast, or these dishes:

Appam Rice flour pancakes
Aviyal Mixed vegetables in a grated coconut sauce
Fish molee Made with coconut milk and vinegar
Konju pappas Shrimp and coconut milk curry
Lamb fry or chicken fry Dry spiced meat curries