Place the ground pork and beef in a large mixing bowl. Add the finely chopped onion, garlic, egg, breadcrumbs, parsley, cumin, red pepper flakes, oregano, thyme, salt and black pepper.
Mix everything gently with your hands until the ingredients are evenly combined. Avoid working the meat more than necessary, as overmixing can make the meatballs dense.
Shape the mixture into 10–12 evenly sized meatballs, approximately the size of a large walnut.
Heat the olive oil and butter in a large, deep frying pan over medium-high heat. Add the meatballs and brown them on all sides, turning carefully. They do not need to be cooked through at this stage. Remove them from the pan and set aside.
Reduce the heat to medium. Using the same pan, add the roughly chopped onion. If the pan is dry, add a small drizzle of olive oil. Cook for approximately 3–4 minutes until softened.
Add the finely chopped garlic and cook for another minute, stirring so it does not burn.
Add the roasted red pepper strips, ground cumin, oregano, thyme, smoked paprika, sweet paprika and sambal oelek. Stir and cook for 1–2 minutes until fragrant.
Pour in the chopped tomatoes and dry white wine. Crumble in ½ chicken stock cube and stir well, scraping up any browned bits from the bottom of the pan.
Return the browned meatballs to the pan, along with any juices that have collected on the plate. Spoon the sauce over them. If necessary, add 50–100 ml of water so that the meatballs are mostly surrounded by sauce.
Bring the sauce to a gentle simmer. Cover the pan with a lid and cook over low heat for approximately 1 hour, turning the meatballs occasionally. The sauce should bubble very gently rather than boil vigorously.
During the final 10 minutes of cooking, stir the tomato passata into the sauce. Continue simmering until the meatballs are tender and the sauce has thickened to your liking. The center of the meatballs should reach at least 71°C (160°F).
Taste the sauce and adjust the seasoning with salt or black pepper if necessary. Remember that the stock cube already contains salt.
Sprinkle with freshly chopped parsley just before serving. Bring the albóndigas to the table in a warm serving dish with plenty of crusty bread for dipping into the sauce.