Stuffed corn tortillas with black beans & sweet corn. Delicious stuffed corn tortillas. Made with non-GMO corn masa. Vegan. Gluten free. Delicious. Authentic. Please recycle. What's a pupusa? Originating from El Salvador, a pupusa is a stuffed corn tortilla filled with delicious goodness, such as black bean & sweet corn. Our tortillas are produced with organic, non-GMO corn masa and are gluten free. Pupusas are traditionally served with a side of curtido (cabbage slaw with vinegar) and salsa roja. Find the recipe for curtido on the side panel. www.trespupusas.com. Stuffed corn tortillas.