In a large bowl, combine cabbages, apples, celery, and apple cider vinegar.
In a small bowl, add lemon juice, mustard powder, garlic powder, Swerve, salt, and cayenne pepper. Whisk to combine.
Pour the lemon juice mixture over the cabbage mix and toss to coat.
Cover with plastic wrap and refrigerate for at least 2 hours, up to 4 hours.
Just before serving, heat up a grill or grill pan. Once hot, add two filets of fish. Cook for approximately 2 to 3 minutes on either side, until cooked through. Depending on the thickness of the filet, you may need to cook the fish longer.
Serve one filet of grilled white fish over half of the apple-celery slaw. Garnish with freshly chopped cilantro.
You can easily make a double or triple this recipe to use throughout the week for lunches. The slaw gets more flavorful the longer it sits!