Grate an onion finely and put it in a bowl with salt, pepper, flour, egg, and minced pork, and mix it well until everything is well mixed into a nice and smooth meat mixture. Put the mixture in the fridge and let it sit. 20-30 minutes before the meatballs are to be fried, take the mixture out and leave it on the kitchen counter. Melt plenty of butter in a pan and shape the meatballs with a tablespoon, frying the meatballs for 5-7 minutes on each side over medium heat. When the meatballs are flipped, spoon melted butter over them. They are now ready to serve.