Roughly chop the chorizo into 1.5 cm (1/2") chunks and process with a stick blender to form a paste. Heat olive oil in a large non-stick skillet over high heat. Sauté onion and garlic for 2 minutes. Add the chorizo and cook for an additional 2 minutes. Stir in the beef and cook until no pink remains. Incorporate tomato paste, cooking briefly for 1 minute. Add potato, spices, thyme, salt, stock, and tomato passata. Bring to a gentle simmer and cook for 15 minutes until the potato is tender and the filling is juicy yet not watery. Mix in green onion, then transfer to a bowl and let cool completely, approximately 2 hours.