Wash the pork lung and pork heart thoroughly under cold running water.
(Optional) Refrigerate overnight for enhanced flavor, then proceed with the following steps.
Place in a large pot with enough salted water to cover them. Add 125 ml vinegar, 1 large onion, 3 bay leaves, 2 carnations, and 5 peppercorns. Bring to a boil over high heat, then reduce to medium heat.
Simmer for approximately 1 hour until the pork lung reaches an internal temperature of 63°C (145°F). Strain the cooking stock through a sieve and reserve it.
Remove the cooked pork lung and pork heart. Remove veins and connective tissue and cut the meat into bite-sized cubes.
In a separate pan, heat a little fat over medium heat. Add 2 tablespoons flour and cook, stirring constantly, for 3-5 minutes until medium brown.
Add the cubed meat to the browned flour. Pour the reserved cooking stock over the meat until barely covered.
Simmer on medium heat for 10 minutes. Season with salt, pepper, and additional vinegar to taste until the sauce is noticeably sour.