Prep ingredients: clean and remove skin from ginger root; cut and save the white part of the green onions, and cut into small pieces the green part of the green onions; sprinkle salt and pepper on both sides of chicken thighs.
Set Instant Pot to 'saute' setting. Sear chicken thighs on one side (sear skin-on side first - doing this will produce some oil at the bottom of the pot and no additional oil is needed), flip and sear the other side. Make sure chicken thighs are not stacked on top of each other. You want to brown each piece on both sides, but no need to fully cook chicken. If needed cook in two batches.
Add chicken stock and water to Instant Pot. Then add garlic, the white part of the green onions, ginger root, Mirin, soy sauce and sesame oil.
Close lid. Set Instant Pot to cook on High Pressure for 20 minutes. Make sure to give it time as it takes a while for the Instant Pot to build and release pressure.
While waiting for broth to cook, add water to a separate small pot and boil water on the stove. After it comes to a boil, gently lower eggs into boiling water and cook for 7 minutes for jammy eggs. (Cook for 9-10 minutes for hard boiled eggs). Remove eggs, rinse in cold water, and peel. Cut eggs into half.
Once the broth is cooked, remove chicken thighs and shred chicken. Discard skin and bones.
Taste broth. If it is too salty, add hot water to diute it. Keep in mind that ramen broth tends to be thick and super flavorful.
Bring Instant Pot back to a boil under the saute setting, and cook ramen noodles in the broth for 2-3 minutes, or until soft.
Assemble ramen noodles, broth, shredded chicken, chopped green onions (the green part that is cut into small pieces in Step 1) and egg in bowls. Serve and enjoy!