Rinse pork shanks under cold, running water. In a deep pot over medium heat, combine pork and enough water to cover. Bring to a boil, skimming any scum that accumulates on top.
Lower heat, cover, and simmer adding more water as needed to maintain 7 cups, for about 1 to 2 hours or until pork shanks are tender. Drain meat, reserving 7 cups of broth.
In a skillet over medium heat, add rice flour and cook, stirring occasionally, until lightly browned and toasted.
In a bowl, combine toasted rice flour and 3/4 cup of the reserved broth and whisk until smooth. Set aside.
In a small bowl, combine annatto powder and ¼ cup of reserved broth. Stir until powder is dissolved and color has dispersed.
In a large pot over medium heat, heat oil. Add onions and garlic and cook until softened.
Add pork shanks and cook, stirring occasionally, until lightly browned. Add fish sauce and cook for about 2 to 3 minutes.
Add the remaining 6 cups of reserved broth and bring to a simmer.
Add annatto water, rice flour mixture, and peanut butter, stirring well to prevent lumps.
Season with salt and pepper to taste.
Continue to simmer for about 10 minutes or until sauce begins to slightly thicken.
Meanwhile, in a pot over medium heat, bring about 4 cups of water to a boil. Add eggplant and blanch for about 1 minute. With a slotted spoon, remove from liquid.
Add long beans and blanch for about 1 minute. With a slotted spoon, remove from liquid.
Add pechay and blanch for about 30 seconds. With a slotted spoon, remove from liquid.
Add vegetables to the pot and continue to cook for about 2 to 3 minutes or until heated through.
Arrange kare-kare on a serving platter and serve with sauteed shrimp paste on the side.