Scrub and trim the ends off the zucchini. Dry with paper towels. Slice thickly, or cut into batons, slice really thickly and quarter the slices; whatever your whim.
Heat oil in frying pan (with cover). Put in the zucchini pieces, toss around in the oil and sprinkle with salt and pepper. Cover and cook for 5 to 10 minutes, shaking the pan from time to time to prevent the zucchini from sticking.
The zucchini is done when it starts to look translucent; do not overcook. If it is not to be served immediately, remove the lid from the pan; otherwise the zucchini will turn disagreeably swampy.
Arabella Boxer, First Slice Your Cookbook, 1964, Courgettes or Marrow
A nice variation is to stir in some sour cream toward the end of cooking.http://macheads2.net/recipes/BasicZucchiniSaute.html