Add a splash of veg oil to a medium pot on medium-high heat. Season the chicken with salt and pepper and lay them into the pot to brown. Do so in batches if they won't all fit. Also, do not try to flip the chicken too early or you'll tear the skin and meat. Once they're browned, the quarters will release from the bottom of the pot on their own. This step should take about 10 minutes per batch. When done, remove the chicken to a plate and set aside.

Drain the oil and burned bits from the pot and add a fresh splash of veg oil. Throw in the onions and let them sweat for a few minutes, then add the garlic and fry another minute. Once fragrant, pour in the chicken stock and fish sauce. Bring the pot to a boil and lay the chicken back in. Try to get the pieces mostly submerged. Turn the heat down to medium-low and let simmer, covered, for 30 minutes.

Put your largest pan on high heat and add a splash of veg oil. Once hot, lay the bok choy in, cut-side down. Let fry for about 5 minutes without touching them, until they're slightly softened and nicely browned on their cut side. Remove the bike choy to a plate and cover with tin foil to keep them warm until ready to serve.

Stir the coconut milk and peanut butter into the pot until they're melted and thoroughly combined into the sauce. Add the beans and several grinds of black pepper. Let simmer a final 5 minutes, then give it a taste and add extra peanut butter and/or fish sauce as needed. Serve with plenty of steamed rice and the seared bok choy.