Heat olive oil in a pressure cooker. Once the oil starts to get hot, add the butter. Continue to heat until the butter and oil mixture starts to bubble.
Saute the onion until tender.
Add the oxtail. Cook each side for 1 minute.
Add tomato paste. Saute the it in tomato paste for 2 minutes.
Pour the beef broth into the pressure cooker. Cover and pressure cook for 30 to 40 minutes.
Add thyme and red wine. Let boil.
Add cubes potato. Continue to cook for 8 to 10 minutes. Note: you can add more beef broth if the liquid starts to dry-up.
Add salt and ground black pepper to taste.
Transfer to a serving bow. Serve.
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