I haven't noticed a lot of street food in L.A. (at least the parts I frequent) except for the food trucks that are now all the rage. But they're in different places all the time and I've not had the chance to sample one yet. When I was in Hong Kong, the street food was great. I didn't try the more exotic foods, but the stuff I did have was cheap and good.
My friend lived in Hong Kong and she raved about the street food and food in general but when I visited I don't remember much about the food... I like Hong Kong style tea snack shops in the states alright though.
The street food in Mexico City is delicious and cheap and everywhere. There are also stands that only operate a few hours a day, we would look for the most packed stands and eat there. Who doesn't love pork?!? LOL. Gorditas and enchildas in Mexico City are totally different from what I am used to in the states. I had the most delicious hot and fresh gorditas... You can also get tamales easily, there are lots of food stands (mobile and not) near convenience stores. And
tortas are really popular, they spread refried beans on the bread but I don't think I can ever taste them...
I also ate
huitlacoche aka Mexico's "corn truffle" which is DELICIOUS and of course vegetarian friendly, lol. And drank tons and tons of fresh juice (soooo cheap and tons of fruit) especially after I got hit with both food poisoning and a cold.
We never made it to Oaxaca but we had chapulines aka grasshoppers at an outdoor market. After we added lemon/lime they were pretty soggy...and it reminded me of eating bugs in general. Kinda mealy. But I had shrimp on a stick at the Xmas themed fair at Zocalo (huge park that goes nuts during the holidays) and the shrimp was giant and juicy. And maybe 2 us dollars. SOOOOO delicious.
In Lima, Peru there isn't as much street food and the offerings are more limited but there are people who sell food on the street (not in trucks though) by carrying around baskets or getting dropped off and just standing and selling. Yes, you can get tamales. The food carts are different kinds of soups/noodles from what I remember and usually near the big markets. More prevalent are stands with grains and corn based drinks...I forget the name...but those stands were very popular in the morning and you can also get avocado breakfast sandwiches at them. Arroz con leche (rice pudding) is usually sold alongside
mazamorra. The food at restaurants is so cheap though (average ~3 us dollars for a 2 or 3 course menu del dia with drink included) you don't need to rely on street food for a budget.
You also see people from bakeries walking around the street or inside markets with trays of food. Normally I would be suspect but other vendors were buying chocolate cakes from one of the bakers so we took a chance it was tasty!
I just made myself hungry...
DC has typical US/east coast food stands like hot dogs and pretzels but they are really geared towards tourists and nothing to write home about. There are 1 or 2 'gourmet' food trucks that travel and a Korean food stand downtown that are popular but I have never eaten at one.