Make the marinade: In a small bowl, put the shallots, lemongrass, soy sauce, fish sauce, chile paste, sugar, five-spice powder, garlic and ginger. Mix well.
Put the ribs in a deep baking dish or roasting pan and add marinade. Using your hands, coat ribs well. Let marinate, refrigerated, for at least 2 hours and preferably overnight, well wrapped. Bring back to room temperature before proceeding.
Heat oven to 450°F. Add 2 cups water to the pan, cover tightly with foil and place pan in oven. Cook for 30 minutes, then reduce heat to 350°F for 1 hour more. When done, the meat should be very tender, nearly but not quite falling off the bone. Remove cover and return to the oven for about 15 minutes until the ribs are nicely browned.
Remove ribs from pan. Pour pan juices into a saucepan and skim fat. Reduce over high heat until somewhat thickened, about 5 minutes. Meanwhile, divide ribs with a sharp knife and pile them onto a platter.
Serve with cooked white rice and pan juices. Garnish with scallions, cilantro and mint sprigs.