In a slow-cooker (recommended) or in a big pot, add in 4 lbs. of oxtail. If using a slow-cooker, fill it with just enough water to cover the meat, and cook on high for 4-5 hours or on low for 8 hours. If using a regular pot, add 10 cups of water to the pot, bring it to a boil, turn the heat down to the lowest level and simmer the oxtail uncovered on low heat for 2.5 to 3 hours.

While the meat is cooking, add 1/2 cup of annatto seeds in a bowl and 1 cup of water. Set this aside and let it soak for 2 hours minimum, or you can even leave it overnight.

When the meat is cooked, it should be very soft and practically falling off the bone, especially when using a slow-cooker. Separate the meat from the broth and set them aside.

In a large pot or Dutch oven, heat 2 to 3 tbsp of vegetable oil over medium heat. When the oil is hot, add 6 cloves of garlic, minced, 1 onion sliced, and sauté this for 3 to 5 minutes stirring occasionally. Season this with 3 tbsp of fish sauce.

Add in 2 cups of the oxtail broth, and 1.5 cups of creamy peanut butter. Mix this well until the mixture is uniform. After this point, keep in mind to continue stirring so that the peanut butter doesn't settle and burn at the bottom of the pot.

Without adding the annatto seeds that have settled at the bottom of the bowl, pour just the red annatto-seed-water that was left soaking earlier. This will add color and a subtle flavor to the dish - annatto is known to have a subtle flavor of being slightly peppery, sweet, and nutty (a little bit like nutmeg).

At this point, you can add as much of the remaining oxtail broth as you'd like, depending on the size of your pot, so it is filled up to two-third of the way up. Save any unused oxtail broth as stock for other dishes.

To thicken the Kare-Kare sauce, add 1/2 to 1 cup of rice flour to the dish, depending on how thick you want it. Mix this in well.

While the sauce simmers and thickens, add 1 lb of long green beans (sitaw), 3 thin eggplants chopped into 1-inch cubes, and 4 to 5 bunches of baby bok choy. Let the vegetables simmer for about 10 to 15 minutes, till they soften.

Turn off the heat, and adjust the salt and pepper to the Kare-Kare sauce according to your taste. Transfer the oxtail pieces to a serving dish or bowl, and spoon the sauce and vegetables over the oxtail meat. Serve with jasmine rice and a side of bagoong, which is a shrimp paste. Enjoy!