Stir together the vinegar, soy sauce, hot pepper paste, garlic, ginger, red pepper flakes, black pepper, sugar, green onions, and yellow onion in a large bowl. Mix in the pork slices, mixing well until completely coated. Place into a resealable plastic bag, squeeze out any excess air, seal, and marinate in the refrigerator at least 3 hours.
Heat the canola oil in a large skillet over medium-high heat. Add the pork slices in batches, and cook until no longer pink in the center, and lightly browned on the outside, about 5 minutes per batch. Be careful when cooking the meat, the spicy fumes will hurt your nose!