While the hole-in-the-wall ambience of S & I Thai can be enough to scare off the average foodie, don’t judge a Thai restaurant by its décor. Locals know the takeout at this hidden gem is perfect for those longing for an affordable, late-night fix of curry-flavored goodness in the Allston-Brighton area. S & I Thai serves up an array of dishes, including a Som Tum (or Papaya Salad for $7.95) that’s so spicy it will literally make you tear up and, of course, their ubiquitous Pad Thai including basil, crispy, and spicy tofu. A basic rule for those on a quest for the perfect Boston-area dive is to check the menu. If it’s in Thai and you have to order by pointing to a lineup of pictures on the wall, it’s a good thing. A menu without English usually means the food is 100% authentic.