Combine the oil, vinegar, tamari and pepper into a jar with a lid and shake vigorously to mix before using.
Toss the spinach in a glass bowl with just enough of the dressing to lightly coat (1 1/2 tablespoons is my ideal), but not weigh down, the greens.
Place the bowl in the microwave for 45 seconds* on the high setting. Toss again and plate right away. (If the greens sit in the warm bowl, they tend to get limp.)
Garnish the salad with cheese, nuts, dried fruits, citrus or cut vegetables, drizzled with additional dressing to taste.
For more tender lettuces, start with a setting of 30 seconds, then toss and determine if you want more wilting. If so, I recommend 10-second bursts so you don't over-wilt them.