Heat a large skillet over over medium high heat, Add 1 tsp of oil over medium heat.
Season the chicken with salt and pepper on both sides. Add the chicken to the hot skillet skin-side down and sear until golden brown, about 3-5 minutes. When nicely browned and no longer sticking to the pan, transfer the chicken to a plate and set aside.
In the same pan, add the onions and sauté for 2-3 minutes. Add the garlic and continue to cook until the onions are translucent, approximately 5-7 minutes. Reduce heat if needed to prevent the onions from burning.
Add water and scrape up the brown bits from the bottom of the pan to deglaze
Stir in vinegar, soy sauce, and brown sugar. Bring to a gentle simmer.
Return the chicken to the skillet, spooning the sauce over the chicken. Reduce heat to maintain a low simmer. Cover and cook for 30 minutes, flipping th chicken halfway through.
Flip the chicken back skin side up and add your potatoes. Cook for 10 minutes or until the potatoes are tender
Taste the sauce and adjust with more sugar or salt, if needed.