In a bowl, combine tripe and enough cold water to cover. Soak in refrigerator overnight. The next day, drain well.
Generously apply salt on tripe and vigorously rub on surfaces. Rinse well under cold, running water, and repeat for about 2 or 3 times.
In a large pot over medium heat, combine 1 liter of water and 2 tablespoons salt. Bring to a boil. Add the tripe and cook for about 10 to 15 minutes. Drain well, discarding liquid. Rinse pot.
In the pot, combine the parboiled tripe, beef bones, and about 8 cups water. Bring to a boil over medium heat, skimming scum that floats on top.
When the broth has cleared, add onion, garlic, ginger, and peppercorns. Lower heat, cover, and cook for about 3 to 4 hours or until desired tenderness. Add more water as needed to maintain about 7 cups.
Remove tripe. Using a fine-mesh sieve, strain broth. Reserve liquid and discard bones and aromatics.
Allow tripe to cool to touch and slice into 1/2-inch thick x 2-inch long strips.
In a pot over medium heat, heat oil. Add onions, garlic, and ginger and cook until softened.
Add tripe and cook, stirring occasionally, for about 3 to 5 minutes.
Add fish sauce and continue to cook for 1 to 2 minutes.
Add rice and cook, stirring regularly, for about 2 to 3 minutes. e.
Add broth and bring to a boil, skimming any foam that may float on top. Lower heat, cover, and cook for about 25 to 30 minutes or until rice grains are softened and have burst.
Season with salt and pepper to taste.
Ladle congee into serving bowls and garnish with chopped onions and fried garlic bits. Serve hot with calamansi.