Mix all the ingredients of the adobo sauce together in a small bowl until the brown sugar is dissolved.
Line the inner lid of the Instant Pot with the sliced onions.
Place the chicken legs on top of the onion rounds.
Pour the adobo sauce all over the chicken.
Close the lid and set the Instant Pot to high pressure cook for 10 minutes.
Once done, the Instant Pot will make a beeping sound. Let the pressure to naturally release for at least 10 more minutes, then quick release the remaining pressure.
Once the Instant Pot makes the beeping sound and is done with the pressure, preheat the oven to 400 degrees Fahrenheit on broil (the top part only with heat).
Open the lid and transfer the chicken legs into a metal pan with wire rack.
Place the chicken legs in the oven for 10 minutes until it becomes golden brown.
While the chicken legs are in the oven, put the Instant Pot on saute and place three eggs (washed) in it in order to make them hard-boiled eggs. Slice the hardboiled eggs after using an egg slicer.
Serve the broiled chicken with rice, eggs, and some soy-vinegar mixture from the Instant Pot.