In a pot over medium heat, heat oil. Add potatoes and cook, stirring occasionally, until lightly browned. Remove from pot and drain on paper towels.
Add onions, garlic, and ginger and cook until softened.
Add baby back ribs and cook, stirring occasionally, until lightly browned.
Add pineapple juice, soy sauce, pineapple tidbits, and water. Bring to a boil, skimming scum that floats on top.
Lower heat, cover, and cook for about 1 11/2 to 2 hours or until meat is fork-tender, adding more water in ½ cup increments as needed.
When the meat is tender, add potatoes and raisins. continue to cook until potatoes are tender.
Season with salt and pepper to taste. Serve hot.