To prepare a sweet and sour pineapple meatballs recipe, you will first need to prepare your ingredients. You will need: 1 pound ground pork, 1 cup chopped pineapple, 2 tablespoons each ketchup and brown sugar, and 1 teaspoon each ground cinnamon and ground nutmeg. To make the pork tenderloin, add 1 tablespoon each chopped onion and chopped celery to the meat mixture. Mix the ingredients until they are well combined. Pour the mixture into 4 large ramekins and cover with plastic wrap. Refrigerate for at least 1 hour, or overnight if possible. Preheat the oven to 375 degrees F (190 degrees C). Cut the pineapple in half lengthwise and remove the pit. Cut each half into 1/4-inch slices. Place the slices on the rimmed baking sheet. Bake for 20 minutes or until tender. Serve warm with your favorite dipping sauce.