1. To toast walnuts: Preheat oven to 350°F. On a small baking sheet, place walnuts in oven until they are fragrant and look a shade darker, about 5 minutes. Remove from oven, and set aside to cool.
2. To make slaw: Strip the ruffly leaves off of the kale's stems. Stack and bunch the leaves together on the cutting board and use the knife to cut across the stack so that you end up with skinny slivers of kale. Put the garlic, lemon juice, oil, and salt in the large bowl, then add the kale and toss it all around with the tongs. Taste it, and add more lemon, oil, or salt to taste.
3. Add the Parmesan cheese and walnuts and serve.