Make the pickled cucumbers. Whisk together the boiling water with rice vinegar, sugar, and salt until the sugar and salt have dissolved. Pour the mixture over the sliced cucumbers and let sit for 30 minutes or overnight in the fridge.
Place the pork belly in a pot and add enough chicken stock or water to cover the pork belly. Add the ginger, garlic, Thai chile, and scallions to the pot and cover. Bring to a boil over high heat, then reduce the heat and simmer on low for 2 hours or until tender.
Meanwhile, make the marinade. Combine all of the ingredients for the marinade including the coconut milk, peanut butter, oil, brown sugar, rice vinegar, red curry paste, mustard, and fish sauce until smooth.
Preheat broiler to high.
Drain the pork and let cool slightly. Cut the pork into bite-sized chunks and pour the marinade on top, gently tossing to coat all sides. Skewer the pork belly and lay the skewers on a baking sheet. Broil the pork until lightly charred on all sides, about 8 minutes.
Meanwhile, make the dipping sauce. Combine the water with rice vinegar, sugar, Thai chile, and lime juice. Set aside.
Transfer the pork belly satay onto a plate and sprinkle crusted peanuts and cilantro on top. Serve with pickled cucumbers and the dipping sauce.