1. Preheat oven to 350°F. Stir together sunflower seeds, 2 tsp. oil, and 2 tsp. seasoning in small bowl. Spread on small baking sheet, and bake 5 to 7 minutes, or until light brown. Set aside.
2. Heat remaining 2 Tbs. oil in large saucepan or Dutch oven over medium-high heat. Add remaining 1 Tbs. seasoning, and cook 30 seconds. Add spinach leaves in 3 or 4 batches, turning with tongs to wilt evenly. Let cook 1 minute, then remove pan from heat, stir in vinegar, and season with salt and pepper, if desired. Sprinkle with sunflower seeds just before serving.