Par-boil the pork untl fork tender. Take out form the water, cool down then slice in chunks. Store in the fridge until ready to cook.
In a bowl, mix together peanut butter, water, hoisin sauce, soy sauce, garlic powder, ginger powder, black pepper, and sesame oil. Set aside
Heat up oil in a wok/pan. Saute onions and garlic for 2-3 minutes. Add the parboiled pork, sliced in chunks. Stir then cover the work to cook for 10minutes. Stir occasionally.
Uncover then add water and peanut butter sauce. Stir, cover, and cook for 15 minutes. Uncover to stir once during the process.
Stir in the potatoes. Cover and cook until potatoes are fork tender.
Stir one last time after potatoes are done.