Preheat the oven to 400°F.
Score the fat of the trimmed pork belly lightly with a sharp knife. Season with salt and pepper.
In a heavy skillet over medium-high heat, sear the pork belly on all sides until the exterior is nicely browned. Transfer to a pot with a lid, add a splash of water or low-sodium broth, cover, and let braise on low heat for 1.5 to 2 hours until tender.
Meanwhile, peel and cut the carrot and parsnip into uniform pieces. Toss them in a bowl with olive oil, salt, pepper, and roughly chopped rosemary and thyme.
Spread the root vegetables on a baking sheet and roast in the preheated oven for 25-30 minutes, stirring halfway through, until they are tender and the edges start to crisp.
For the poached egg, bring a small pot of water to a gentle simmer, swirl the water gently, and carefully crack in the egg. Poach for about 3-4 minutes for a soft yolk. Remove with a slotted spoon and drain on paper towels.
Assemble the dish by slicing the tender pork belly into bite-sized pieces, arrange the roasted root vegetables on a plate, and top with the sliced pork belly. Finally, place the poached egg on top, allowing the yolk to enrich the flavors. Garnish with extra rosemary or thyme if desired.