Toast the potatoes in a heavy saucepan over medium-high heat, stirring constantly. Cover with boiling water to an inch higher than the potatoes. Let rest for one hour.
Heat the lard over medium heat until rippling, add the pork and cook until browned, and remove with a slotted spoon to a bowl to catch the juices.
To the same fat in the pan, add the garlic, onions, and chile pastes, stirring well to combine. Add the reserved pork, stirring well to combine. Add the potatoes and their soaking water. Taste and add salt and freshly ground black pepper. Cover and cook over low heat for about 35 minutes, stirring often as the potatoes tend to stick to the bottom of the pan. Add water a little bit at a time if needed.
Add the remaining ingredients and cook for about another 10 minutes.