Prepare the Kale: In a large bowl, add the chopped kale. Massage the kale leaves with your hands for about 1-2 minutes until they start to soften and reduce in volume.
Make the Dressing: In a small bowl or jar, whisk together the olive oil, lemon juice, Dijon mustard, minced garlic, salt, and black pepper until well combined.
Combine Ingredients: Pour the dressing over the massaged kale and toss to coat evenly.
Add Toppings: Add the cherry tomatoes, red onion, grated Parmesan cheese, and toasted nuts if using. Toss gently to combine. If using avocado, add it just before serving to prevent browning.
Serve: Divide the salad into individual bowls or serve on a large platter. Garnish with extra Parmesan cheese if desired.