Heat Annatto oil in a soup pot or pressure cooker.
Put the garlic in once the oil gets hot. Cook until the garlic turns light brown.
Add the beef shank. Cook one side for 30 seconds to one minute. Turn it over to cook the other side for about the same time.
Pour water. Let boil.
Add the onion, tomato, and beef cube. Stir.
Add the lemongrass. Cover the pressure cooker and cook for 30 minutes. Note: if using a regular soup pot, cook the beef in low heat for 2 to 3 hours. Add more water if needed.
Safely remove the cover of the pressure cooker. Apply heat and bring the mixture to a boil.
Stir-in the jackfruit and cook for 5 minutes.
Add the peppers. Cook for 2 to 3 minutes.
Pour the contents of the sinigang mix package. Stir. Add fish sauce. Cook for 3 to 5 minutes.
Transfer to a serving bowl. Serve.
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