Place chicken, onion, carrots, celery, parsley and peppercorns in a dutch oven (4 - 6 quart size is good) or stockpot. Fill with water to about 2" above ingredients. Cover pot and bring to a boil on stovetop over medium-high heat, remove lid, sprinkle in the salt, reduce heat, and maintain a slow simmer for 60–90 minutes. (See next step if you want shredded chicken in your finished soup.)
Optional step: remove the chicken at 45 minutes, let cool slightly, remove meat from the bones, and set aside on a dish for later (refrigerate). Return the bones to the pot to continue cooking for the 60–90 minute total time.
Strain the solids from the broth, pressing to extract as much broth as possible. I do this by setting a colander over a large bowl, then spooning in the solids, then pouring over the liquid. Pick through the solids to save bits of meat and or carrots for your furry friends, then discard the solids.
Give the pot a quick rinse then return the broth to it. Heat to boiling, add the uncooked, diced carrots and reduce heat to a simmer. Cook for a couple minutes then add the pearl couscous (or cooked rice or cooked noodles) and shredded chicken. Heat through and serve.