Picnics are the spice of life for author James Michener

Ostrich pate in South Africa; rice outside a rural Uzbek teahouse; pizza in Scotland. When you've gone the gastronomical gamut, simplicity can be appetizing. And the simplicity of a good old-fashioned picnic is a favorite of novelist James Michener.

By the calculations of his wife, Mari, he has traveled - and eaten - everywhere but the South Pole, and he still likes picnics best.

''My husband and I love picnics. But we don't just mean a sandwich and a Coke. He likes things festive but not fussy,'' explains Mari, who has been nearly everywhere but South America with her husband.

In a recent interview that included a wide range of topics, the Micheners became most animated when asked about their taste in food. Mr. Michener, who is writing his new book ''Texas'' out of an ample rented home here, whipped out a lap-size atlas, tracking down the exact locations of their favorite picnics around the globe.

Meanwhile Mari reminisced about the meals that have spiced their travels throughout the years in which he wrote such books as ''Caravans,'' ''Iberia,'' ''Hawaii,'' and ''The Source.''

She conjured the distant memory of dinner with a group of strangers at dusk on a ditch bank in a remote region of Uzbekistan, in the Soviet Union, during the writing of ''Caravans.''

''It was an out-of-the-blue event. They saw us and beckoned us over to sit with them on the bare dirt of a teahouse (chaihana) floor,'' she said. ''We ate the most delicious rice, similar to pilaf, with lamb bits cooked in a woklike pot. It was charming. It was not a particularly exotic dish, but it was the thought and the friendly men. You don't have to speak the same language to enjoy a meal,'' Mrs. Michener says.

Another of their favorite picnic memories was set in the Turkish countryside, where they vacationed after Mr. Michener had completed his work on ''The Source.'' Traveling with the United States naval attache from Israel, the party ''took turns choosing the site of each picnic . . . the site; that's important, '' she says.

''We would buy bread, fresh fruit, tomatoes, canned tins of meat - nothing exotic, but still good, lots of delicious goat cheese,'' she says.

The most memorable picnic on that trip happened on a rural hillside across from a castle and under a huge tree. But it was memorable largely for a recipe Mr. Michener concocted when it was discovered that their car had a leak in the gas tank. ''My husband told me to chew three or four sticks of gum; I've always kept some in my purse since then. He chewed some newspaper.'' Putting the two together with some cotton, she says, Michener successfully plugged the hole in the tank, and the party had their picnic and still made it back to town.

On more domestic picnics, where the Micheners have a home to work out of, potato salad is a must. ''My wife makes the best potato salad in the world,'' attests Michener, who suggests that it is the recipe she should offer for publication here.

Mrs. Michener's Potato Salad

Two rules govern a good potato salad, she says:

* Use only fresh ingredients.

* The potatoes should weigh about 1 1/2 times the weight of all the other ingredients combined.

The ingredients include boiled, peeled, and cubed potatoes, and the following added to the cook's taste: celery, onions, green pepper, chopped sweet pickles, a sauce of French's Salad Mustard and mayonnnaise with ''about 1/3 more mustard than mayonnaise.''

Finally, she says, ''It must have celery seeds and ground pepper.''