How to Make It
Preheat oven to 325°F.
Place walnuts on a rimmed baking sheet or in a large ovenproof skillet, and break up walnuts slightly into smaller pieces with your hands. Add maple syrup, sesame seeds, olive oil, and, if desired, red pepper. Sprinkle with black pepper and 1 teaspoon salt, and toss until evenly coated.
Place in oven, and roast at 325°F, stirring occasionally, until walnuts are golden brown and maple syrup is caramelized, 15 to 20 minutes. Remove from heat, and immediately sprinkle with sumac and remaining 1/2 teaspoon salt, tossing to coat. Let cool completely before serving, about 10 minutes.