Vietnamese noodles called "bún" with boiled chicken are very very delicious. It's the popular breakfast in Hanoi. You could try in the street and you maybe are addicted on this food! jaja
A bow of the noodles "bún gà" costs 25.000 - 30.000 VND. It's not only cheap but also delicious, hot and the smell helps you really relaxed when you feel tired or sleepy ! jaja