Heat vegetable oil in a large pot over medium heat.
Add the chopped onion and garlic, and cook until softened and fragrant.
Add the pork chunks and cook until they are browned on all sides.
Pour in the water or chicken broth, ensuring that the pork is covered.
Bring to a boil, then reduce the heat to low. Cover and let it simmer for about 1 to 1.5 hours, or until the pork is tender.
Stir in the finely chopped cassava leaves (or spinach).
Continue to cook for another 30-40 minutes, stirring occasionally. The cassava leaves should become tender and blend with the pork.
If using, stir in the crushed peanuts and soy sauce.
Season with ground black pepper and salt to taste.
Enjoy your meal!