Char chiles over a gasflame or under a broiler, turning occasionally,until blackened all over (this adds a smokyflavor and makes the skins easy to remove).
Let cool. Using a small knife, scrape skinfrom chiles; discard. Coarsely chop chiles(for a milder salsa, discard seeds).
Make a paste by mincing garlic and1 teaspoon salt on a work surface, scraping withthe side of knife occasionally.
Add chilesand finely chop, then add mint and finelychop.
Transfer to a bowl; stir in oil. Seasonwith more salt, if desired. DO AHEAD: Salsacan be made 1 day ahead. Cover; chill.Return to room temperature before using.
Place chicken and broth in a largeheavy pot.
Add water just to cover chicken.Bring to a simmer over high heat, skimmingthe surface occasionally (foam can addbitter flavors to soup; discard it as youskim). Reduce heat to medium-low; simmer,continuing to skim surface occasionally,for 5 minutes.
Add corn cobs, halved onion,garlic, carrot, celery, peppercorns, bayleaves, and 2 teaspoons salt. Reduce heat to lowand simmer until breast meat is just cookedthrough, 15-20 minutes.
Transfer chicken to a cutting board; letcool slightly.
Cut off breast meat; set aside(cooking breast meat longer will make ittough). Return chicken to pot. Simmer overlow heat until legs and thighs are cookedthrough, about 20 minutes longer.
Remove pot from heat.
Transfer chickento a platter; let cool slightly. Strain broththrough a fine-mesh sieve into another largepot; discard solids. Shred all chicken meat,discarding skin and bones.
Bring strained broth to a simmer.
Addcorn kernels and cook until heated through,about 3 minutes.
Add red onion; cook untilcrisp-tender, about 5 minutes.
Add chicken;simmer, stirring occasionally, until heatedthrough, about 5 minutes. Season with salt.
Divide soup among warmbowls.
Garnish with tomato and tortillachips. Squeeze lime wedges over; addwedges to soup.
Serve, passing chile-mintsalsa and sea salt alongside.