Cut the pork shoulder into 3 x 3 cm cubes. Place in a bowl and add the marinade: chopped onion, minced garlic, chopped ginger, Sichuan pepper, and soy sauce. Mix well and refrigerate for at least 30 minutes.
Once marinated, drain the pork but keep the marinade! Start a caramel over high heat with the sugar and strawberry vinegar in a clean saucepan. The caramel is ready when the vinegar becomes thick and bubbly. Add the pork cubes, stir well, and cook for 2 minutes to coat the meat. Add the marinade and reduce the heat to medium. Cook for 8 minutes. Then add the veal stock, stir, and remove the pork. Let the sauce reduce for about 15 minutes until it reaches a glossy, coating consistency.
Finely slice the spring onion on a bias.
Serve the caramel pork with Thai rice. Garnish with the sliced spring onion and toasted sesame seeds.