In a large pot, place the oxtail, beef tripe, and beef skin. Cover with water and bring to a boil. After 15 mins, discard the water in a strainer and rinse the meat.
Boil again the oxtail, beef tripe and beef skin in hot water, salt and lemon grass. After 15 mins, discard the water in a strainer and rinse the meat.
Put the boiled meat in a pressure cooker adding 2 liters of water, green onions, whole black pepper, and fish sauce. You can also add the beef cubes for a more meaty flavor. Boil for about 35 minutes then remove the beef tripe. Boil the oxtail and beef skin again for about 15 mins. Once cooked, set aside the meat and reserve the broth.
In a separate pot, boil water and add a tablespoon of salt. Blanch the string beans, green beans, pechay, eggplant and banana heart until tender but still crisp. Set aside.
In a large pan or pot, heat the annatto oil. Sauté the onion and garlic until fragrant. Then pour in about 5-6 cups of the reserved broth, bring to a boil.
Add the peanut butter and ground peanuts, stirring well to combine. Slowly add the rice flour, stirring constantly to avoid lumps, stirring continuously until the sauce thickens.
Add the fish sauce, and season with salt and pepper to taste. If the sauce is too thick, you can add more water to reach your desired consistency.
Add the cooked oxtail, tripe, and beef skin to the sauce. Simmer for about 10-15 minutes, allowing the flavors to meld together. Add the blanched vegetables to the pot, stirring gently to combine.
Serve the Kare Kare hot with steamed rice and bagoong (fermented shrimp paste) on the side.