Umami Broth with Buckwheat and Vegetables

toasted sesame oil

red miso

diced sweet onion

(1-in.) piece fresh ginger, peeled and grated

garlic cloves, minced

water

unsalted chicken stock

dried shiitake mushrooms

large eggs in shells

uncooked buckwheat groats, rinsed and drained

medium carrot, cut into 1/4-in.-thick half-moons

baby bok choy, stalks sliced crosswise into 1/2-in. pieces, leaves left whole

green onions, cut into 1-in. pieces

rice vinegar