Trim any excess fat from the pork belly if necessary. Pat it dry with paper towels.
In a small bowl, combine the kosher salt, black pepper, sugar, paprika, garlic powder, dried thyme, and crushed red pepper flakes (if using).
Rub the seasoning mixture all over the pork belly, making sure it is evenly coated.
Place the seasoned pork belly in a large resealable plastic bag or wrap it tightly in plastic wrap. Refrigerate for at least 5 days, turning the meat every day to ensure even curing.
After the curing period, remove the pork belly from the refrigerator and rinse off the seasoning under cold water. Pat it dry with paper towels.
Place the pork belly on a wire rack in a cool, dry place with good air circulation. Allow it to air dry for 1-2 weeks, depending on the thickness of the meat and desired texture. The speck should feel firm to the touch.
Once dried, you can cook the speck by slicing it thinly and pan-frying it until crispy, or it can be used as a flavorful ingredient in various dishes.
Enjoy your meal!