Preheat the broiler and place the bell peppers on a broiler pan lined with foil and cook, turning occasionally until the skin is blistered and black all over. Remove from the broiler and wrap the foil around the peppers until cool enough to handle. Halve, remove the skin, ribs and seeds and cut into strips. Let the juices run into the pan as it will enhance the vinaigrette.
If not using left-over pork, place the pork slices covered with 1 Tbsp. olive oil, salt and pepper under the broiler and cook for about 10 minutes, turning over the slices half way through. Pork should read 140 degrees.
Warm a heavy bottomed skillet with 1 Tbsp. olive oil and add the red onion, cabbage, celery, garlic, salt and black pepper. Cook, stirring frequently for 10 minutes or until all is tender.
Divide the cabbage mixture among 4 plates. Arrange the peppers and pork on top. Drizzle each with balsamic vinegar and pan juices and sprinkle with 1 Tbsp, of mozzarella cheese. I also added celery leaves and a ton of fresh basil as garnish.