1. Slice the pork into thin strips no more than 1/4 inch wide. Trim away and discard any excess fat. Set the pork aside.
2. Heat the oil in an extra-deep 12-inch skillet over medium heat. Add the pork and cook, stirring frequently, until it is no longer pink, 4 to 5 minutes.
3. Meanwhile, cut the scallions into 1-inch pieces. Just before the pork is cooked through, add the scallions and garlic. Cook, stirring until the scallions are crisp-tender, about 1 minute. Remove the skillet from the heat and set it aside.
4. Divide the lettuce among four dinner plates. Remove and discard and tough core from the cabbage. Thinly slice the cabbage and then cut the shreds into bite-size pieces. Scatter the cabbage evenly over the lettuce on each plate.
5. Grate the carrots on the largest holes of a box grater (or use a food processor). Scatter the grated carrots carrots evenly over the cabbage. Thinly slice the cucumber and divide the slices evenly among the plates, scattering the slices over the carrots.
6. Arrange the pork and scallion mixture on top of each salad and drizzle with the dressing. (Or pass the dressing at the table.) Garnish each salad with 1 tbsp chopped peanuts/almonds, if desired.