Step 1: Peel 3 tangerines and slice them into 1-inch rounds, removing any seeds. Set aside.
Step 2: Juice 1 tangerine (separate from the sliced tangerines) and mix with 2 tablespoons olive oil and 1 teaspoon chopped rosemary. Whisk until well combined. Season to taste with salt and pepper.
Step 3: In a large bowl, combine 1/2 pound fresh spinach, the tangerine slices and 1/4 cup dried cranberries with the dressing and toss gently to coat. Divide salad among salad plates.