Just came back from a field trip with my daughter's preschool to Buen Gusto Restaurante in East Boston (295 Bennington, right in Day Square). The mother of the owners is the chef, and she demonstrated how she makes papusas from scratch, then we ate them. We had some that were beans and cheese, some that were zucchini and cheese, and some that were the "typical" Salvadoran pork. The latter ones were absolutely fantastic. The usual sides of Salvadoran cole slaw and salsa were not too spicy (don't know if they toned it down for the niños) but very tasty. I love the texture and mild acidity the slaw adds to the papusas.
We also sampled some fried yucca with chicharrones. I never really like chicharrones much, but they were fine. The yucca was wonderful. This platter is served with fresh lime slices, tomato and radish garnish. Yum. We also had lots of horchata to wash it all down, mild and sweet.
The restaurant itself is lovely. They have some beautiful photos on the wall from El Salvador.
Can't comment on how service would be for a more typical dining excursion, but they were certainly very welcoming to our group of preschoolers. They are open at 10am every day......didn't notice the closing time. They do have a couple of breakfast items on the menu, one of which sounded like a breakfast burrito, the other was scrambled eggs with Salvadoran sides: avocado, fried plantains, beans, etc.
I'll be going back with the spouse for a lunch or evening run sometime.