Boil the sliced tripe strips. Once cooked, drain, setting the broth aside. Meanwhile, in a pan, sauté chopped onion and garlic (using only half the head of garlic) in oil, along with the ginger cut into thin strips. When the onion turns translucent, add the tripe and fish sauce, and let it cook for a few minutes to develop flavor. Then add the two varieties of rice and continue sautéing everything for another five minutes, stirring well. Cover with the broth set aside earlier, topping up with warm water if needed, and bring to a boil. As soon as the broth starts boiling, lower the heat and continue simmering with the pan covered for about half an hour, or until the rice has broken down, adding water as needed. Season with salt and pepper, add calamondin orange juice, and serve piping hot, garnished with fried garlic and chopped fresh spring onions.