In a mixing bowl, combine the rice vinegar, salt, and 2 tsp. sugar, and whisk to combine. Add sliced cucumbers, cover with film and set aside.
Heat a wok or large skillet until a drop of water dances on the surface and disappears. Add the oil, onions, and garlic.
As soon as it is fragrant, add the ground pork and 2 Tbsp of sugar. Stir-fry, until the ground pork crisps into browned bits.
Take the mixture off the heat and stir in the fish sauce until completely absorbed. Stir in black pepper.
On a large platter, place the caramelized pork in the center, surrounded by the pickled cucumbers.
Serve with rice and garnishes for building lettuce wraps. Optional garnishes include: mint, Thai basil, cilantro, dry roasted peanuts, sriracha, limes.
