Preheat oven to 400 degrees F. Line large baking sheet with foil or parchment paper. Place asparagus on baking sheet and drizzle with oil. Toss to coat all the spears then spread them out. Season with salt and pepper. Roast until crisp-tender, about 7-10 minutes. (Mine were ready at 7 minutes.) Transfer asparagus to serving platter and allow to cool.
Using a microplane or other implement, zest the tangerines until you have the desired amount of peel. Cut these tangerines to get the juice needed for the dressing.
Whisk together tangerine juice, zest, rice vinegar, sesame oil, garlic, and fresh ginger in small measuring cup or bowl. Season dressing to taste with salt and pepper. Whisk again.
Using a sharp knife, remove the peel from the tangerine (or orange), then section the fruit so that all white pith and section dividers are removed.
Place tangerine pieces atop asparagus in an eye-pleasing arrangement. Drizzle the asparagus and tangerine segments with the dressing. Top the salad with the sliced green onions and cashews.