Soup Noodle!
Soup noodle in Thailand is the perfect food, hands down. It's the best breakfast, especially if you are hung over. Protein, fiber, and satisfying rice noodle starch with mad hydration, salt, sugar, and plenty of anti-oxident and vitamin C rich Thai chilis! Eating spicy foods makes you sweat, raises your metabolism and makes you feel alive.
People say the best street food in Chiang Mai is Kaow Soi, which is Burmese-style curry noodle soup with coconut milk and fried wheat noodles on top, but I found it is too heavy to eat every day. I'm about the clear broth with fresh bean sprouts and herbs. The broth usually has a secret combination of garlic, tamarind, crushed peanuts, sugar, soy sauce, cilantro, etc. They cook the noodles in the broth for 30 seconds and then pour broth on top with some vegetables and frsh herbs. Then they put some Roasted meat or some fish balls or something in there and you are good. I even got to like the Laos- style kind thats made with dried pig's blood cakes!
Or you can get it veg, the best of which is found at a small restaurant two block behind Three Kings monument.

You always have to adjust with sugar, fish sauce, chili sauce and vinegar to get your shit straight!

The best places to get soup noodle are dingy holes-in-the-wall that make this place look like a palace.