In a serving bowl, toss together the spinach leaves, Mandarin orange pieces, diced red onions and chopped walnuts.
Prepare the vinaigrette by mixing the olive oil, vinegar, soy sauce, sesame seeds, ginger, sugar, and pepper together in a resealable container or jar.
Pour the soy-sesame vinaigrette over the top of the Asian Spinach Salad and serve.