Heat a large pot over medium high heat; add oil.

Place the onion, carrots, and ginger in the stock pot. Sear the veggies on all sides to caramelize.

Add garlic and cook just until it begins to brown.

Pour in the chicken broth and bring to a boil. Lower heat, cover pot, and simmer for one hour.

Pour broth through a fine-mesh sieve to remove the solids; reserve for another use. Taste the broth and salt as needed.

Divide hot broth between four individual bowls and top with fresh sliced scallions and sliced mushrooms.