Cover breadcrumbs with milk and allow to soak for 10 minutes. Lightly squeeze and combine in a mixing bowl with the pork, parmesan, egg, parsley, garlic, salt and pepper. Mix with your hands to evenly distribute the ingredients. Heat a small skillet over high heat and cook a small amount of the meatball mixture. Taste for seasoning and adjust if necessary. Portion into 8 to 10 pieces, rub the palms of your hands with olive oil and roll into balls.
Heat a wide bottom pan over high heat. Add the olive oil and sear meatballs on two sides. Remove from the heat and set aside. Add the onions and peppers and reduce heat to medium. Season with a pinch of salt. Cook, stirring often, until the onions and peppers are wilted and caramelized. Add the meatballs back to the pan along with the sprig of rosemary. Pour in the chicken stock, cover and cook over low heat for 20 minutes. Divide the meatballs between individual warm plates. Reduce the broth in the pan to a light sauce like consistency and add the vinegar during the last minute of cooking to brighten the flavors. Spoon the onions, pepper and broth over the top of meatballs. Garnish with the chopped parsley.
Enjoy with a glass of Cakebread Cellars Guajolote.