In a large bowl, stir together yogurt, mayo, dressing mix, and vinegar. Using the 4-in-1 Mandoline, set with the 1.5 mm slicer plate, thinly slice cabbage. You should have about 5 cups. Add to bowl; stir to combine. If making ahead, keep refrigerated, up to 3 days.
Using 4-in-1 Mandoline, slice onion. Slice buns open and toast, if desired.
Fill each bun with pork; add 1⁄4 cup coleslaw to each sandwich. Top with onion. Serve with remaining coleslaw on the side.
Per serving: Calories 470, Fat 18 g (Saturated 3.5 g, Trans 0.1 g), Cholesterol 85 mg, Sodium 580 mg, Carbohydrate 41 g (Fiber 3 g, Sugars 13 g), Protein 33 g.
For added tang and freshness, give the red onion a little more love. Add sliced red onion to 4-Cup Prep Bowl. Using 2-in-1 Citrus Press, squeeze in juice from 1 lemon, then add a pinch each of sugar and salt. Using your hands, gently toss and squeeze onion to help soften it slightly.