First, start by cutting the large pieces of fat off of each oxtail using a sharp knife.
Next, place the oxtails inside of a bowl and add vinegar, salt, pepper and granulated garlic. Marinate the oxtails while you prepare the rest of the ingredients.
Chop and dice the bell pepper and onion.
Finely mince the garlic cloves.
Set the instant pot function to saute and add oil.
Once the oil is hot, add the oxtails and cook for 3 minutes on each side. Transfer the oxtails to a plate for now.
Add the flour, bell pepper and onion. Whisk together until the diced onions become translucent.
Add the minced garlic and saute for an additional 15 seconds or until fragrant.
Pour in the red wine and cook for 3 minutes to reduce while whisking together to break up any lumps from the flour.
Add the oxtails back into the instant pot.
Pour in the tomato sauce, tomato paste, beef broth and add salt to taste.
Use a wooden spoon to deglaze the bottom of the instant pot. Do not skip this important step, otherwise you will get a burn notice.
Cancel the saute function and close the lid. Cook on high pressure for 30 minutes with a 10 minute natural release. Quick release any remaining pressure.
Open the lid and add the frozen cassava.
Close the lid and cook on high pressure for 20 minutes with a 5 minute natural release.
Top with fresh parsley if desired and enjoy!