In a small pot place all chilis/capsicum then submerge in 2 cups water. Boil until soft and tender.
Place cooked chilis in a blender and add ⅔ cups of water used for boiling chilies. Blend into a smooth paste. Set aside.
Cut beef shanks into 3x3 in. blocks and season with salt. In a large pot, heat oil over medium heat and sear beef shank for 2-3 minutes on all sides. Remove beef from pot and set aside.
Using same pot, add more oil if needed, sauté onion and garlic. Add tomato paste and oregano then stir to incorporate. Pour beef stock and add seared beef shanks.
In a small cheese cloth, place cinnamon stick, pepper corn, coriander seeds, and bay leaves. Tie to secure cheese cloth and add in the pot with beef.
Cover the pot with lid and simmer-cook for 30 minutes. Add blended chilies and mix to incorporate then continue cooking for additional 30 minutes until beef is pull-apart tender. (Season with salt if needed)
Remove cheese cloth with spices and disregard. Separate beef from the sauce. Pull apart beef using forks until shredded and place sauce in a bowl. Set aside.