Veggie burgers in Hanoi lack a lot. I have yet to come across a veggie burger there that isn't some sort of sloppy mishmash of vegetables, batter and usually cheese (yuck!). Oh. And fried.
Even outside Vietnam, no veggie burger comes close to what you can get at Harvey's. Canada's answer to fast-food giants Burger King and McDonald's, Harvey's grills your burger on an open flame right in front of your eyes. And they have stations set up where you can dictate to a worker exactly what you want going into your burger.
My veggie burger was constructed with tomatoes, onions, pickles, hot peppers, lettuce, mustard, and barbecue sauce all stacked between a whole wheat bun. I skipped the fries so I could stuff down two of these. Here's some photos to help you salivate.