Wash and dry the spinach until you're absolutely sure it's clean; spinach can hold a lot of grit. When you're sure it's clean and dry, put it in a salad bowl, and sprinkle it with salt, and squeeze the leaves gently with your hands. You'll find that the spinach "deflates," or sort of gets a bit limp and reduces in volume. Add the scallions to the bowl. Pour on the olive oil, and toss the salad thoroughly. Add the lemon juice, and toss again. Top with the pecans, and serve.