Preheat the oven to 150°C (300°F). Season the pork belly with salt, black pepper, thyme, and rosemary. Place it in a roasting pan, skin side up, and drizzle with olive oil. Roast for 2.5 to 3 hours until tender.

Make the Spaetzle

In a bowl, mix the spaetzle flour, eggs, and milk until smooth. Bring a large pot of salted water to a boil. Use a spaetzle maker or a slotted spoon to drop the batter into the water. Cook until they float to the surface, about 2-3 minutes. Remove with a slotted spoon and set aside.

Sauté Spring Onions

In a pan, heat a bit of olive oil over medium heat. Add the chopped spring onions and sauté until soft and slightly caramelized, about 5 minutes.

Prepare the Cider Gastrique

In a saucepan, combine the apple cider vinegar and sugar. Bring to a boil and reduce to a simmer until it thickens slightly, about 10 minutes.

Serve

Slice the pork belly and serve it on a plate with spaetzle, sautéed spring onions, sauerkraut, and drizzled with cider gastrique.